diff --git a/zokrates_cli/examples/arrays/update.zok b/zokrates_cli/examples/arrays/update.zok
index ef660b33..149f5075 100644
--- a/zokrates_cli/examples/arrays/update.zok
+++ b/zokrates_cli/examples/arrays/update.zok
@@ -5,5 +5,5 @@ def foo(field[3] a) -> (field):
 def main() -> (field, field):
 	field[3] a = [0, 0, 0]
 	field res = foo(a)
-	a[1] == 0
+	assert(a[1] == 0)
 	return res, a[1]
diff --git a/zokrates_cli/examples/arrays/update_with_call.zok b/zokrates_cli/examples/arrays/update_with_call.zok
index fcc3eb1a..a50b7daa 100644
--- a/zokrates_cli/examples/arrays/update_with_call.zok
+++ b/zokrates_cli/examples/arrays/update_with_call.zok
@@ -5,5 +5,5 @@ def main(field a) -> (field, field):
 	field[2] result = [0, 0]
 	field r = foo(a)
 	result[1] = r
-	result[1] == r
+	assert(result[1] == r)
 	return result[1], r
\ No newline at end of file
diff --git a/zokrates_cli/examples/book/field_overflow.zok b/zokrates_cli/examples/book/field_overflow.zok
index 796c5b6d..1b208553 100644
--- a/zokrates_cli/examples/book/field_overflow.zok
+++ b/zokrates_cli/examples/book/field_overflow.zok
@@ -1,4 +1,4 @@
 def main() -> ():
     field pMinusOne = 21888242871839275222246405745257275088548364400416034343698204186575808495616
-    0 - 1 == pMinusOne
+    assert(0 - 1 == pMinusOne)
     return
\ No newline at end of file
diff --git a/zokrates_cli/examples/book/hashexample_updated.zok b/zokrates_cli/examples/book/hashexample_updated.zok
index a74363fd..42ed341c 100644
--- a/zokrates_cli/examples/book/hashexample_updated.zok
+++ b/zokrates_cli/examples/book/hashexample_updated.zok
@@ -2,6 +2,6 @@ import "hashes/sha256/512bitPacked" as sha256packed
 
 def main(private field a, private field b, private field c, private field d) -> ():
 	field[2] h = sha256packed([a, b, c, d])
-	h[0] == 263561599766550617289250058199814760685
-	h[1] == 65303172752238645975888084098459749904
+	assert(h[0] == 263561599766550617289250058199814760685)
+	assert(h[1] == 65303172752238645975888084098459749904)
 	return
\ No newline at end of file
diff --git a/zokrates_cli/examples/book/side_effects.zok b/zokrates_cli/examples/book/side_effects.zok
index 70d67409..0941a2d6 100644
--- a/zokrates_cli/examples/book/side_effects.zok
+++ b/zokrates_cli/examples/book/side_effects.zok
@@ -5,5 +5,5 @@ def incr(field a) -> (field):
 def main() -> ():
     field x = 1
     field res = incr(x)
-    x == 1 // x has not changed
+    assert(x == 1) // x has not changed
     return
\ No newline at end of file
diff --git a/zokrates_cli/examples/bool_and.zok b/zokrates_cli/examples/bool_and.zok
index d7017044..7ed3a460 100644
--- a/zokrates_cli/examples/bool_and.zok
+++ b/zokrates_cli/examples/bool_and.zok
@@ -3,5 +3,5 @@
 def main(field a, field b) -> (field):
     field y = if a + 2 == 3 && a * 2 == 2 then 1 else 0 fi
     field z = if y == 1 && 1-y == 0 then y else 1 fi
-    b == 1
+    assert(b == 1)
     return a
\ No newline at end of file
diff --git a/zokrates_cli/examples/bool_or.zok b/zokrates_cli/examples/bool_or.zok
index 664b7eea..77457eac 100644
--- a/zokrates_cli/examples/bool_or.zok
+++ b/zokrates_cli/examples/bool_or.zok
@@ -2,6 +2,6 @@
 def main(field a, field b) -> (field):
     field y = if a + 2 == 4 || b * 2 == 2 then 1 else 0 fi
     field z = if y == 1 || y == 0 then y else 1 fi
-    z == 1
+    assert(z == 1)
     return z
 
diff --git a/zokrates_cli/examples/comments.zok b/zokrates_cli/examples/comments.zok
index 082932df..af9d8070 100644
--- a/zokrates_cli/examples/comments.zok
+++ b/zokrates_cli/examples/comments.zok
@@ -2,6 +2,6 @@
 def main(field a) -> (field): // a needs to be 1
   field b = a + 5 // inline comment
   field c = a + b + a + 4
-  a == 1 // another inline comment
+  assert(a == 1) // another inline comment
   field d = a + c + a + b
   return b + c + d
diff --git a/zokrates_cli/examples/conditions.zok b/zokrates_cli/examples/conditions.zok
index 526239b1..d6f0051b 100644
--- a/zokrates_cli/examples/conditions.zok
+++ b/zokrates_cli/examples/conditions.zok
@@ -1,6 +1,19 @@
+struct Foo {
+	field a
+}
+
+struct Bar {
+	Foo[1] foo
+}
+
+def isEqual(field a, field b) -> (bool):
+	return a == b
+
 def main(field a) -> (field):
   field b = (a + 5) * 6
-  2 * b == a * 12 + 60
+  assert(2 * b == a * 12 + 60)
   field c = 7 * (b + a)
-  c == 7 * b + 7 * a
-  return b + c
+  assert(isEqual(c, 7 * b + 7 * a))
+  field k = if [1, 2] == [3, 4] then 1 else 3 fi
+  assert([Bar { foo : [Foo { a: 42 }]}] == [Bar { foo : [Foo { a: 42 }]}])
+  return b + c
\ No newline at end of file
diff --git a/zokrates_cli/examples/error/assert.zok b/zokrates_cli/examples/error/assert.zok
new file mode 100644
index 00000000..aa2fb018
--- /dev/null
+++ b/zokrates_cli/examples/error/assert.zok
@@ -0,0 +1,5 @@
+def assert() -> ():
+	return
+
+def main() -> ():
+	return
\ No newline at end of file
diff --git a/zokrates_cli/examples/factorization.zok b/zokrates_cli/examples/factorization.zok
index 1cba7214..31824a9b 100644
--- a/zokrates_cli/examples/factorization.zok
+++ b/zokrates_cli/examples/factorization.zok
@@ -1,5 +1,5 @@
 // a and b are factorization of c
 def main(field c, private field a, private field b) -> ():
   field d = a * b
-  c == d
+  assert(c == d)
   return
diff --git a/zokrates_cli/examples/imports/import.zok b/zokrates_cli/examples/imports/import.zok
index a40727e1..194b3c50 100644
--- a/zokrates_cli/examples/imports/import.zok
+++ b/zokrates_cli/examples/imports/import.zok
@@ -7,5 +7,5 @@ import "./bar"
 def main() -> (field):
 	MyBar my_bar = MyBar {}
 	Bar bar = Bar {}
-	my_bar == bar
+	assert(my_bar == bar)
 	return foo() + bar()
\ No newline at end of file
diff --git a/zokrates_cli/examples/left_side_call.zok b/zokrates_cli/examples/left_side_call.zok
index b06d556b..43aac4b4 100644
--- a/zokrates_cli/examples/left_side_call.zok
+++ b/zokrates_cli/examples/left_side_call.zok
@@ -2,5 +2,5 @@ def foo() -> (field):
 	return 1
 
 def main() -> ():
-	foo() + (1 + 44*3) == 1
+	assert(foo() + (1 + 44*3) == 1)
 	return
diff --git a/zokrates_cli/examples/merkleTree/pedersenPathProof3.zok b/zokrates_cli/examples/merkleTree/pedersenPathProof3.zok
index c4d91429..5ab66329 100644
--- a/zokrates_cli/examples/merkleTree/pedersenPathProof3.zok
+++ b/zokrates_cli/examples/merkleTree/pedersenPathProof3.zok
@@ -22,7 +22,7 @@ def main(bool[256] rootDigest, private bool[256] leafDigest, private bool[3] dir
 	preimage = multiplex(directionSelector[2], currentDigest, PathDigest2)
 	currentDigest = hash(preimage)
 
-	rootDigest == currentDigest
+	assert(rootDigest == currentDigest)
 
 	return
 
diff --git a/zokrates_cli/examples/merkleTree/sha256PathProof3.zok b/zokrates_cli/examples/merkleTree/sha256PathProof3.zok
index 4cdea787..808d3adf 100644
--- a/zokrates_cli/examples/merkleTree/sha256PathProof3.zok
+++ b/zokrates_cli/examples/merkleTree/sha256PathProof3.zok
@@ -23,7 +23,7 @@ def main(field treeDepth, bool[256] rootDigest, private bool[256] leafDigest, pr
 	currentDigest = sha256(lhs, rhs)
 	counter = counter + 1
 
-	counter == treeDepth 
-	rootDigest == currentDigest
+	assert(counter == treeDepth)
+	assert(rootDigest == currentDigest)
 
 	return
\ No newline at end of file
diff --git a/zokrates_cli/examples/multiple_witnesses.zok b/zokrates_cli/examples/multiple_witnesses.zok
index 134faf24..3723f107 100644
--- a/zokrates_cli/examples/multiple_witnesses.zok
+++ b/zokrates_cli/examples/multiple_witnesses.zok
@@ -1,4 +1,4 @@
 // this code does not need to be flattened
 def main(field x, field a, field b) -> (field):
-  a == b * 7
+  assert(a == b * 7)
   return x + a + b
diff --git a/zokrates_cli/examples/no_flatten.zok b/zokrates_cli/examples/no_flatten.zok
index 0688c448..3f86e52d 100644
--- a/zokrates_cli/examples/no_flatten.zok
+++ b/zokrates_cli/examples/no_flatten.zok
@@ -1,6 +1,6 @@
 // this code does not need to be flattened
 def main(field x, field y, field z) -> (field):
   field a = x + 3*y - z *2 - x * 12
-  3*y - z *2 - x * 12 == a - x
-  (x + y) - ((z + 3*x) - y) == (x - y) + ((2*x - 4*y) + (4*y - 2*z))
+  assert(3*y - z *2 - x * 12 == a - x)
+  assert((x + y) - ((z + 3*x) - y) == (x - y) + ((2*x - 4*y) + (4*y - 2*z)))
   return x
diff --git a/zokrates_cli/examples/pow.zok b/zokrates_cli/examples/pow.zok
index ba622d72..7d157bae 100644
--- a/zokrates_cli/examples/pow.zok
+++ b/zokrates_cli/examples/pow.zok
@@ -1,16 +1,16 @@
 def main() -> ():
   field x = 2**4
-  x == 16
+  assert(x == 16)
   x = x**2
-  x == 256
+  assert(x == 256)
   field y = 3**3
-  y == 27
+  assert(y == 27)
   field z = y**2
-  z == 729
+  assert(z == 729)
   field a = 5**2
-  a == 25
+  assert(a == 25)
   a = a**2
-  a == 625
+  assert(a == 625)
   a = 5**5
-  a == 3125
+  assert(a == 3125)
   return
diff --git a/zokrates_cli/examples/propagate_call.zok b/zokrates_cli/examples/propagate_call.zok
index ea3435d4..02518cd0 100644
--- a/zokrates_cli/examples/propagate_call.zok
+++ b/zokrates_cli/examples/propagate_call.zok
@@ -1,5 +1,5 @@
 def foo(field a, field b) -> (field, field):
-	a == b + 2
+	assert(a == b + 2)
 	return a, b
 
 def main() -> (field):
diff --git a/zokrates_cli/examples/sudoku/sudoku_checker.zok b/zokrates_cli/examples/sudoku/sudoku_checker.zok
index fa692c9f..d86c9e3b 100644
--- a/zokrates_cli/examples/sudoku/sudoku_checker.zok
+++ b/zokrates_cli/examples/sudoku/sudoku_checker.zok
@@ -20,32 +20,32 @@ def countDuplicates(field e11,field e12,field e21,field e22) -> (field):
   return duplicates
 
 // returns 0 for x in (1..4)
-def validateInput(field x) -> (field):
-  return (x-1)*(x-2)*(x-3)*(x-4)
+def validateInput(field x) -> (bool):
+  return (x-1)*(x-2)*(x-3)*(x-4) == 0
 
 // variables naming: box'row''column'
 def main(field a21, field b11, field b22, field c11, field c22, field d21, private field a11, private field a12, private field a22, private field b12, private field b21, private field c12, private field c21, private field d11, private field d12, private field d22) -> (bool):
 
   // validate inputs
-  0 == validateInput(a11)
-  0 == validateInput(a12)
-  0 == validateInput(a21)
-  0 == validateInput(a22)
+  assert(validateInput(a11))
+  assert(validateInput(a12))
+  assert(validateInput(a21))
+  assert(validateInput(a22))
 
-  0 == validateInput(b11)
-  0 == validateInput(b12)
-  0 == validateInput(b21)
-  0 == validateInput(b22)
+  assert(validateInput(b11))
+  assert(validateInput(b12))
+  assert(validateInput(b21))
+  assert(validateInput(b22))
 
-  0 == validateInput(c11)
-  0 == validateInput(c12)
-  0 == validateInput(c21)
-  0 == validateInput(c22)
+  assert(validateInput(c11))
+  assert(validateInput(c12))
+  assert(validateInput(c21))
+  assert(validateInput(c22))
 
-  0 == validateInput(d11)
-  0 == validateInput(d12)
-  0 == validateInput(d21)
-  0 == validateInput(d22)
+  assert(validateInput(d11))
+  assert(validateInput(d12))
+  assert(validateInput(d21))
+  assert(validateInput(d22))
 
   field duplicates = 0 // globally counts duplicate entries in boxes, rows and columns
 
diff --git a/zokrates_cli/examples/test1.zok b/zokrates_cli/examples/test1.zok
index 054fe3bc..3429b140 100644
--- a/zokrates_cli/examples/test1.zok
+++ b/zokrates_cli/examples/test1.zok
@@ -3,11 +3,11 @@ def main(field x) -> (field):
   field a = 5
   field b = 7
   field c = if a == b then 4 else 3 fi
-  c == 3
+  assert(c == 3)
   field d = if a == 5 then 1 else 2 fi
-  d == 1
+  assert(d == 1)
   field e = if a < b then 5 else 6 fi
-  e == 5
+  assert(e == 5)
   field f = if b < a then 7 else 8 fi
-  f == 8
+  assert(f == 8)
   return x
diff --git a/zokrates_cli/examples/waldo.zok b/zokrates_cli/examples/waldo.zok
index afa9721b..38a304d3 100644
--- a/zokrates_cli/examples/waldo.zok
+++ b/zokrates_cli/examples/waldo.zok
@@ -3,12 +3,13 @@
 // * we don't enforce only one number being non-prime, so there could be multiple Waldos
 
 def isWaldo(field a, field p, field q) -> (bool):
-  // make sure that neither `p` nor `q` is `1`
-  (!(p == 1) && !(q == 1)) == true
+  // make sure that p and q are both not one
+  assert(p != 1 && q != 1)
 
   // we know how to factor a
   return a == p * q
 
+// define all
 def main(field[3] a, private field index, private field p, private field q) -> (bool):
   // prover provides the index of Waldo
   return isWaldo(a[index], p, q)
\ No newline at end of file
diff --git a/zokrates_cli/tests/code/no_return.zok b/zokrates_cli/tests/code/no_return.zok
index 2519aa03..1d939baf 100644
--- a/zokrates_cli/tests/code/no_return.zok
+++ b/zokrates_cli/tests/code/no_return.zok
@@ -1,3 +1,3 @@
 def main(field a, field b) -> ():
-	a==b
+	assert(a == b)
 	return
\ No newline at end of file
diff --git a/zokrates_cli/tests/code/sha_round.zok b/zokrates_cli/tests/code/sha_round.zok
index a2222a40..743191e1 100644
--- a/zokrates_cli/tests/code/sha_round.zok
+++ b/zokrates_cli/tests/code/sha_round.zok
@@ -9,6 +9,6 @@ def main(private bool[256] expected) -> (field):
  	
  	bool[256] IV  = [false, true, true, false, true, false, true, false, false, false, false, false, true, false, false, true, true, true, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, false, true, true, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, true, true, true, false, true, false, false, false, false, true, false, true, false, false, true, true, true, true, false, false, false, true, true, false, true, true, true, false, true, true, true, true, false, false, true, true, false, true, true, true, false, false, true, false, true, false, true, false, false, true, false, true, false, true, false, false, true, true, true, true, true, true, true, true, false, true, false, true, false, false, true, true, true, false, true, false, false, true, false, true, false, false, false, true, false, false, false, false, true, true, true, false, false, true, false, true, false, false, true, false, false, true, true, true, true, true, true, true, true, false, false, true, true, false, true, true, false, false, false, false, false, true, false, true, false, true, true, false, true, false, false, false, true, false, false, false, true, true, false, false, false, false, false, true, true, true, true, true, true, false, false, false, false, false, true, true, true, true, false, true, true, false, false, true, true, false, true, false, true, false, true, true, false, true, false, true, true, false, true, true, true, true, true, false, false, false, false, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, false, true]
 
-	expected == sha256([...a, ...b], IV)
+	assert(expected == sha256([...a, ...b], IV))
 
 	return 1
\ No newline at end of file
diff --git a/zokrates_core/src/absy/from_ast.rs b/zokrates_core/src/absy/from_ast.rs
index ecfae3b4..f44dbe49 100644
--- a/zokrates_core/src/absy/from_ast.rs
+++ b/zokrates_core/src/absy/from_ast.rs
@@ -262,23 +262,8 @@ impl<'ast, T: Field> From<pest::AssertionStatement<'ast>> for absy::StatementNod
     fn from(statement: pest::AssertionStatement<'ast>) -> absy::StatementNode<T> {
         use absy::NodeValue;
 
-        match statement.expression {
-            pest::Expression::Binary(e) => match e.op {
-                pest::BinaryOperator::Eq => absy::Statement::Condition(
-                    absy::ExpressionNode::from(*e.left),
-                    absy::ExpressionNode::from(*e.right),
-                ),
-                _ => unimplemented!(
-                    "Assertion statements should be an equality check, found {}",
-                    statement.span.as_str()
-                ),
-            },
-            _ => unimplemented!(
-                "Assertion statements should be an equality check, found {}",
-                statement.span.as_str()
-            ),
-        }
-        .span(statement.span)
+        absy::Statement::Assertion(absy::ExpressionNode::from(statement.expression))
+            .span(statement.span)
     }
 }
 
@@ -389,7 +374,14 @@ impl<'ast, T: Field> From<pest::BinaryExpression<'ast>> for absy::ExpressionNode
                 box absy::ExpressionNode::from(*expression.left),
                 box absy::ExpressionNode::from(*expression.right),
             ),
-            o => unimplemented!("Operator {:?} not implemented", o),
+            // rewrite (a != b)` as `!(a == b)`
+            pest::BinaryOperator::NotEq => absy::Expression::Not(
+                box absy::Expression::Eq(
+                    box absy::ExpressionNode::from(*expression.left),
+                    box absy::ExpressionNode::from(*expression.right),
+                )
+                .span(expression.span.clone()),
+            ),
         }
         .span(expression.span)
     }
diff --git a/zokrates_core/src/absy/mod.rs b/zokrates_core/src/absy/mod.rs
index 0101e387..86b80582 100644
--- a/zokrates_core/src/absy/mod.rs
+++ b/zokrates_core/src/absy/mod.rs
@@ -299,7 +299,7 @@ pub enum Statement<'ast, T> {
     Return(ExpressionListNode<'ast, T>),
     Declaration(VariableNode<'ast>),
     Definition(AssigneeNode<'ast, T>, ExpressionNode<'ast, T>),
-    Condition(ExpressionNode<'ast, T>, ExpressionNode<'ast, T>),
+    Assertion(ExpressionNode<'ast, T>),
     For(
         VariableNode<'ast>,
         ExpressionNode<'ast, T>,
@@ -317,7 +317,7 @@ impl<'ast, T: fmt::Display> fmt::Display for Statement<'ast, T> {
             Statement::Return(ref expr) => write!(f, "return {}", expr),
             Statement::Declaration(ref var) => write!(f, "{}", var),
             Statement::Definition(ref lhs, ref rhs) => write!(f, "{} = {}", lhs, rhs),
-            Statement::Condition(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
+            Statement::Assertion(ref e) => write!(f, "assert({})", e),
             Statement::For(ref var, ref start, ref stop, ref list) => {
                 write!(f, "for {} in {}..{} do\n", var, start, stop)?;
                 for l in list {
@@ -346,7 +346,7 @@ impl<'ast, T: fmt::Debug> fmt::Debug for Statement<'ast, T> {
             Statement::Definition(ref lhs, ref rhs) => {
                 write!(f, "Definition({:?}, {:?})", lhs, rhs)
             }
-            Statement::Condition(ref lhs, ref rhs) => write!(f, "Condition({:?}, {:?})", lhs, rhs),
+            Statement::Assertion(ref e) => write!(f, "Assertion({:?})", e),
             Statement::For(ref var, ref start, ref stop, ref list) => {
                 write!(f, "for {:?} in {:?}..{:?} do\n", var, start, stop)?;
                 for l in list {
diff --git a/zokrates_core/src/flatten/mod.rs b/zokrates_core/src/flatten/mod.rs
index 50fdd17c..f3b0f0fc 100644
--- a/zokrates_core/src/flatten/mod.rs
+++ b/zokrates_core/src/flatten/mod.rs
@@ -575,9 +575,6 @@ impl<'ast, T: Field> Flattener<'ast, T> {
                 )
             }
             BooleanExpression::FieldEq(box lhs, box rhs) => {
-                // We know from semantic checking that lhs and rhs have the same type
-                // What the expression will flatten to depends on that type
-
                 // Wanted: (Y = (X != 0) ? 1 : 0)
                 // X = a - b
                 // # Y = if X == 0 then 0 else 1 fi
@@ -616,6 +613,53 @@ impl<'ast, T: Field> Flattener<'ast, T> {
 
                 res
             }
+            BooleanExpression::UintEq(box lhs, box rhs) => {
+                // We reduce each side into range and apply the same approach as for field elements
+
+                // Wanted: (Y = (X != 0) ? 1 : 0)
+                // X = a - b
+                // # Y = if X == 0 then 0 else 1 fi
+                // # M = if X == 0 then 1 else 1/X fi
+                // Y == X * M
+                // 0 == (1-Y) * X
+
+                let name_y = self.use_sym();
+                let name_m = self.use_sym();
+
+                assert!(lhs.metadata.clone().unwrap().should_reduce.to_bool());
+                assert!(rhs.metadata.clone().unwrap().should_reduce.to_bool());
+
+                let lhs = self
+                    .flatten_uint_expression(symbols, statements_flattened, lhs)
+                    .get_field_unchecked();
+                let rhs = self
+                    .flatten_uint_expression(symbols, statements_flattened, rhs)
+                    .get_field_unchecked();
+
+                let x = FlatExpression::Sub(box lhs, box rhs);
+
+                statements_flattened.push(FlatStatement::Directive(FlatDirective::new(
+                    vec![name_y, name_m],
+                    Solver::ConditionEq,
+                    vec![x.clone()],
+                )));
+                statements_flattened.push(FlatStatement::Condition(
+                    FlatExpression::Identifier(name_y),
+                    FlatExpression::Mult(box x.clone(), box FlatExpression::Identifier(name_m)),
+                ));
+
+                let res = FlatExpression::Sub(
+                    box FlatExpression::Number(T::one()),
+                    box FlatExpression::Identifier(name_y),
+                );
+
+                statements_flattened.push(FlatStatement::Condition(
+                    FlatExpression::Number(T::zero()),
+                    FlatExpression::Mult(box res.clone(), box x),
+                ));
+
+                res
+            }
             BooleanExpression::Le(box lhs, box rhs) => {
                 let lt = self.flatten_boolean_expression(
                     symbols,
@@ -1851,24 +1895,22 @@ impl<'ast, T: Field> Flattener<'ast, T> {
                     None => {}
                 }
             }
-            ZirStatement::Condition(lhs, rhs) => {
-                // flatten expr1 and expr2 to n flattened expressions with n the number of primitive types for expr1
-                // add n conditions to check equality of the n expressions
+            ZirStatement::Assertion(e) => {
+                // naive approach: flatten the boolean to a single field element and constrain it to 1
 
-                let lhs = self
-                    .flatten_expression(symbols, statements_flattened, lhs)
-                    .get_field_unchecked();
-                let rhs = self
-                    .flatten_expression(symbols, statements_flattened, rhs)
-                    .get_field_unchecked();
+                let e = self.flatten_boolean_expression(symbols, statements_flattened, e);
 
-                if lhs.is_linear() {
-                    statements_flattened.push(FlatStatement::Condition(lhs, rhs));
-                } else if rhs.is_linear() {
-                    // swap so that left side is linear
-                    statements_flattened.push(FlatStatement::Condition(rhs, lhs));
+                if e.is_linear() {
+                    statements_flattened.push(FlatStatement::Condition(
+                        e,
+                        FlatExpression::Number(T::from(1)),
+                    ));
                 } else {
-                    unreachable!()
+                    // swap so that left side is linear
+                    statements_flattened.push(FlatStatement::Condition(
+                        FlatExpression::Number(T::from(1)),
+                        e,
+                    ));
                 }
             }
             ZirStatement::MultipleDefinition(vars, rhs) => {
diff --git a/zokrates_core/src/semantics.rs b/zokrates_core/src/semantics.rs
index 3a4c314e..949e72b7 100644
--- a/zokrates_core/src/semantics.rs
+++ b/zokrates_core/src/semantics.rs
@@ -875,27 +875,21 @@ impl<'ast> Checker<'ast> {
                 }
                 .map_err(|e| vec![e])
             }
-            Statement::Condition(lhs, rhs) => {
-                let checked_lhs = self
-                    .check_expression(lhs, module_id, &types)
-                    .map_err(|e| vec![e])?;
-                let checked_rhs = self
-                    .check_expression(rhs, module_id, &types)
+            Statement::Assertion(e) => {
+                let e = self
+                    .check_expression(e, module_id, &types)
                     .map_err(|e| vec![e])?;
 
-                if checked_lhs.get_type() == checked_rhs.get_type() {
-                    Ok(TypedStatement::Condition(checked_lhs, checked_rhs))
-                } else {
-                    Err(ErrorInner {
+                match e {
+                    TypedExpression::Boolean(e) => Ok(TypedStatement::Assertion(e)),
+                    e => Err(ErrorInner {
                         pos: Some(pos),
                         message: format!(
-                            "Cannot compare {} of type {:?} to {} of type {:?}",
-                            checked_lhs,
-                            checked_lhs.get_type(),
-                            checked_rhs,
-                            checked_rhs.get_type(),
+                            "Expected {} to be of type bool, found {}",
+                            e,
+                            e.get_type(),
                         ),
-                    })
+                    }),
                 }
                 .map_err(|e| vec![e])
             }
@@ -1543,6 +1537,54 @@ impl<'ast> Checker<'ast> {
                     (TypedExpression::Boolean(e1), TypedExpression::Boolean(e2)) => {
                         Ok(BooleanExpression::BoolEq(box e1, box e2).into())
                     }
+                    (TypedExpression::Array(e1), TypedExpression::Array(e2)) => {
+                        if e1.get_type() == e2.get_type() {
+                            Ok(BooleanExpression::ArrayEq(box e1, box e2).into())
+                        } else {
+                            Err(ErrorInner {
+                                pos: Some(pos),
+                                message: format!(
+                                    "Cannot compare {} of type {} to {} of type {}",
+                                    e1,
+                                    e1.get_type(),
+                                    e2,
+                                    e2.get_type()
+                                ),
+                            })
+                        }
+                    }
+                    (TypedExpression::Struct(e1), TypedExpression::Struct(e2)) => {
+                        if e1.get_type() == e2.get_type() {
+                            Ok(BooleanExpression::StructEq(box e1, box e2).into())
+                        } else {
+                            Err(ErrorInner {
+                                pos: Some(pos),
+                                message: format!(
+                                    "Cannot compare {} of type {} to {} of type {}",
+                                    e1,
+                                    e1.get_type(),
+                                    e2,
+                                    e2.get_type()
+                                ),
+                            })
+                        }
+                    }
+                    (TypedExpression::Uint(e1), TypedExpression::Uint(e2)) => {
+                        if e1.get_type() == e2.get_type() {
+                            Ok(BooleanExpression::UintEq(box e1, box e2).into())
+                        } else {
+                            Err(ErrorInner {
+                                pos: Some(pos),
+                                message: format!(
+                                    "Cannot compare {} of type {} to {} of type {}",
+                                    e1,
+                                    e1.get_type(),
+                                    e2,
+                                    e2.get_type()
+                                ),
+                            })
+                        }
+                    }
                     (e1, e2) => Err(ErrorInner {
                         pos: Some(pos),
                         message: format!(
@@ -3136,9 +3178,12 @@ mod tests {
         // def bar():
         //   2 == foo()
         // should fail
-        let bar_statements: Vec<StatementNode<Bn128Field>> = vec![Statement::Condition(
-            Expression::FieldConstant(Bn128Field::from(2)).mock(),
-            Expression::FunctionCall("foo", vec![]).mock(),
+        let bar_statements: Vec<StatementNode<Bn128Field>> = vec![Statement::Assertion(
+            Expression::Eq(
+                box Expression::FieldConstant(Bn128Field::from(2)).mock(),
+                box Expression::FunctionCall("foo", vec![]).mock(),
+            )
+            .mock(),
         )
         .mock()];
 
@@ -3535,9 +3580,12 @@ mod tests {
         // def bar():
         //   1 == foo()
         // should fail
-        let bar_statements: Vec<StatementNode<Bn128Field>> = vec![Statement::Condition(
-            Expression::FieldConstant(Bn128Field::from(1)).mock(),
-            Expression::FunctionCall("foo", vec![]).mock(),
+        let bar_statements: Vec<StatementNode<Bn128Field>> = vec![Statement::Assertion(
+            Expression::Eq(
+                box Expression::FieldConstant(Bn128Field::from(1)).mock(),
+                box Expression::FunctionCall("foo", vec![]).mock(),
+            )
+            .mock(),
         )
         .mock()];
 
diff --git a/zokrates_core/src/static_analysis/flatten_complex_types.rs b/zokrates_core/src/static_analysis/flatten_complex_types.rs
index 035cea54..eb2c7b81 100644
--- a/zokrates_core/src/static_analysis/flatten_complex_types.rs
+++ b/zokrates_core/src/static_analysis/flatten_complex_types.rs
@@ -248,14 +248,9 @@ pub fn fold_statement<'ast, T: Field>(
                 .map(|v| zir::ZirStatement::Declaration(v))
                 .collect()
         }
-        typed_absy::TypedStatement::Condition(left, right) => {
-            let left = f.fold_expression(left);
-            let right = f.fold_expression(right);
-            assert_eq!(left.len(), right.len());
-            left.into_iter()
-                .zip(right.into_iter())
-                .map(|(left, right)| zir::ZirStatement::Condition(left, right))
-                .collect()
+        typed_absy::TypedStatement::Assertion(e) => {
+            let e = f.fold_boolean_expression(e);
+            vec![zir::ZirStatement::Assertion(e)]
         }
         typed_absy::TypedStatement::For(..) => unreachable!(),
         typed_absy::TypedStatement::MultipleDefinition(variables, elist) => {
@@ -555,6 +550,68 @@ pub fn fold_boolean_expression<'ast, T: Field>(
             let e2 = f.fold_boolean_expression(e2);
             zir::BooleanExpression::BoolEq(box e1, box e2)
         }
+        typed_absy::BooleanExpression::ArrayEq(box e1, box e2) => {
+            let e1 = f.fold_array_expression(e1);
+            let e2 = f.fold_array_expression(e2);
+
+            assert_eq!(e1.len(), e2.len());
+
+            e1.into_iter().zip(e2.into_iter()).fold(
+                zir::BooleanExpression::Value(true),
+                |acc, (e1, e2)| {
+                    zir::BooleanExpression::And(
+                        box acc,
+                        box match (e1, e2) {
+                            (
+                                zir::ZirExpression::FieldElement(e1),
+                                zir::ZirExpression::FieldElement(e2),
+                            ) => zir::BooleanExpression::FieldEq(box e1, box e2),
+                            (zir::ZirExpression::Boolean(e1), zir::ZirExpression::Boolean(e2)) => {
+                                zir::BooleanExpression::BoolEq(box e1, box e2)
+                            }
+                            (zir::ZirExpression::Uint(e1), zir::ZirExpression::Uint(e2)) => {
+                                zir::BooleanExpression::UintEq(box e1, box e2)
+                            }
+                            _ => unreachable!(),
+                        },
+                    )
+                },
+            )
+        }
+        typed_absy::BooleanExpression::StructEq(box e1, box e2) => {
+            let e1 = f.fold_struct_expression(e1);
+            let e2 = f.fold_struct_expression(e2);
+
+            assert_eq!(e1.len(), e2.len());
+
+            e1.into_iter().zip(e2.into_iter()).fold(
+                zir::BooleanExpression::Value(true),
+                |acc, (e1, e2)| {
+                    zir::BooleanExpression::And(
+                        box acc,
+                        box match (e1, e2) {
+                            (
+                                zir::ZirExpression::FieldElement(e1),
+                                zir::ZirExpression::FieldElement(e2),
+                            ) => zir::BooleanExpression::FieldEq(box e1, box e2),
+                            (zir::ZirExpression::Boolean(e1), zir::ZirExpression::Boolean(e2)) => {
+                                zir::BooleanExpression::BoolEq(box e1, box e2)
+                            }
+                            (zir::ZirExpression::Uint(e1), zir::ZirExpression::Uint(e2)) => {
+                                zir::BooleanExpression::UintEq(box e1, box e2)
+                            }
+                            _ => unreachable!(),
+                        },
+                    )
+                },
+            )
+        }
+        typed_absy::BooleanExpression::UintEq(box e1, box e2) => {
+            let e1 = f.fold_uint_expression(e1);
+            let e2 = f.fold_uint_expression(e2);
+
+            zir::BooleanExpression::UintEq(box e1, box e2)
+        }
         typed_absy::BooleanExpression::Lt(box e1, box e2) => {
             let e1 = f.fold_field_expression(e1);
             let e2 = f.fold_field_expression(e2);
diff --git a/zokrates_core/src/static_analysis/mod.rs b/zokrates_core/src/static_analysis/mod.rs
index bf163a70..41c67a99 100644
--- a/zokrates_core/src/static_analysis/mod.rs
+++ b/zokrates_core/src/static_analysis/mod.rs
@@ -55,7 +55,7 @@ impl<'ast, T: Field> TypedProgram<'ast, T> {
         let r = VariableAccessRemover::apply(r);
 
         // convert to zir, removing complex types
-        let zir = Flattener::flatten(r.clone());
+        let zir = Flattener::flatten(r);
 
         // optimize uint expressions
         let zir = UintOptimizer::optimize(zir);
diff --git a/zokrates_core/src/static_analysis/propagation.rs b/zokrates_core/src/static_analysis/propagation.rs
index 5bc0da6a..15477e7b 100644
--- a/zokrates_core/src/static_analysis/propagation.rs
+++ b/zokrates_core/src/static_analysis/propagation.rs
@@ -112,13 +112,10 @@ impl<'ast, T: Field> Folder<'ast, T> for Propagator<'ast, T> {
             TypedStatement::Definition(TypedAssignee::Member(..), _) => {
                 unreachable!("struct update should have been replaced with full struct redef")
             }
-            // propagate lhs and rhs for conditions
-            TypedStatement::Condition(e1, e2) => {
+            // propagate the boolean
+            TypedStatement::Assertion(e) => {
                 // could stop execution here if condition is known to fail
-                Some(TypedStatement::Condition(
-                    self.fold_expression(e1),
-                    self.fold_expression(e2),
-                ))
+                Some(TypedStatement::Assertion(self.fold_boolean_expression(e)))
             }
             // only loops with variable bounds are expected here
             // we stop propagation here as constants maybe be modified inside the loop body
@@ -957,6 +954,11 @@ impl<'ast, T: Field> Folder<'ast, T> for Propagator<'ast, T> {
         &mut self,
         e: BooleanExpression<'ast, T>,
     ) -> BooleanExpression<'ast, T> {
+        // Note: we only propagate when we see constants, as comparing of arbitrary expressions would lead to
+        // a lot of false negatives due to expressions not being in a canonical form
+        // For example, `2 * a` is equivalent to `a + a`, but our notion of equality would not detect that here
+        // These kind of reduction rules are easier to apply later in the process, when we have canonical representations
+        // of expressions, ie `a + a` would always be written `2 * a`
         match e {
             BooleanExpression::Identifier(id) => match self
                 .constants
diff --git a/zokrates_core/src/static_analysis/uint_optimizer.rs b/zokrates_core/src/static_analysis/uint_optimizer.rs
index 3315fa4e..5b856f05 100644
--- a/zokrates_core/src/static_analysis/uint_optimizer.rs
+++ b/zokrates_core/src/static_analysis/uint_optimizer.rs
@@ -53,6 +53,24 @@ fn force_no_reduce<'ast, T: Field>(e: UExpression<'ast, T>) -> UExpression<'ast,
 }
 
 impl<'ast, T: Field> Folder<'ast, T> for UintOptimizer<'ast, T> {
+    fn fold_boolean_expression(
+        &mut self,
+        e: BooleanExpression<'ast, T>,
+    ) -> BooleanExpression<'ast, T> {
+        match e {
+            BooleanExpression::UintEq(box left, box right) => {
+                let left = self.fold_uint_expression(left);
+                let right = self.fold_uint_expression(right);
+
+                let left = force_reduce(left);
+                let right = force_reduce(right);
+
+                BooleanExpression::UintEq(box left, box right)
+            }
+            e => fold_boolean_expression(self, e),
+        }
+    }
+
     fn fold_uint_expression(&mut self, e: UExpression<'ast, T>) -> UExpression<'ast, T> {
         if e.metadata.is_some() {
             return e;
@@ -398,17 +416,17 @@ impl<'ast, T: Field> Folder<'ast, T> for UintOptimizer<'ast, T> {
                     )],
                 },
             },
-            // we need to put back in range to assert
-            ZirStatement::Condition(lhs, rhs) => {
-                match (self.fold_expression(lhs), self.fold_expression(rhs)) {
-                    (ZirExpression::Uint(lhs), ZirExpression::Uint(rhs)) => {
-                        vec![ZirStatement::Condition(
-                            force_reduce(lhs).into(),
-                            force_reduce(rhs).into(),
-                        )]
-                    }
-                    (lhs, rhs) => vec![ZirStatement::Condition(lhs, rhs)],
-                }
+            ZirStatement::Assertion(BooleanExpression::UintEq(box left, box right)) => {
+                let left = self.fold_uint_expression(left);
+                let right = self.fold_uint_expression(right);
+
+                // we can only compare two unsigned integers if they are in range
+                let left = force_reduce(left);
+                let right = force_reduce(right);
+
+                vec![ZirStatement::Assertion(BooleanExpression::UintEq(
+                    box left, box right,
+                ))]
             }
             s => fold_statement(self, s),
         }
diff --git a/zokrates_core/src/static_analysis/unroll.rs b/zokrates_core/src/static_analysis/unroll.rs
index f3dc70c9..00400446 100644
--- a/zokrates_core/src/static_analysis/unroll.rs
+++ b/zokrates_core/src/static_analysis/unroll.rs
@@ -84,13 +84,12 @@ impl<'ast> Unroller<'ast> {
 
                     match head {
                         Access::Select(head) => {
-                            statements.insert(TypedStatement::Condition(
+                            statements.insert(TypedStatement::Assertion(
                                 BooleanExpression::Lt(
                                     box head.clone(),
                                     box FieldElementExpression::Number(T::from(size)),
                                 )
                                 .into(),
-                                BooleanExpression::Value(true).into(),
                             ));
 
                             ArrayExpressionInner::Value(
@@ -1089,13 +1088,12 @@ mod tests {
             assert_eq!(
                 u.fold_statement(s),
                 vec![
-                    TypedStatement::Condition(
+                    TypedStatement::Assertion(
                         BooleanExpression::Lt(
                             box FieldElementExpression::Number(Bn128Field::from(1)),
                             box FieldElementExpression::Number(Bn128Field::from(2))
                         )
                         .into(),
-                        BooleanExpression::Value(true).into()
                     ),
                     TypedStatement::Definition(
                         TypedAssignee::Identifier(Variable::field_array(
@@ -1227,13 +1225,12 @@ mod tests {
             assert_eq!(
                 u.fold_statement(s),
                 vec![
-                    TypedStatement::Condition(
+                    TypedStatement::Assertion(
                         BooleanExpression::Lt(
                             box FieldElementExpression::Number(Bn128Field::from(1)),
                             box FieldElementExpression::Number(Bn128Field::from(2))
                         )
                         .into(),
-                        BooleanExpression::Value(true).into()
                     ),
                     TypedStatement::Definition(
                         TypedAssignee::Identifier(Variable::with_id_and_type(
diff --git a/zokrates_core/src/static_analysis/variable_access_remover.rs b/zokrates_core/src/static_analysis/variable_access_remover.rs
index 79f2ca5b..991740b1 100644
--- a/zokrates_core/src/static_analysis/variable_access_remover.rs
+++ b/zokrates_core/src/static_analysis/variable_access_remover.rs
@@ -39,7 +39,7 @@ impl<'ast, T: Field> VariableAccessRemover<'ast, T> {
                     _ => unreachable!(),
                 };
 
-                self.statements.push(TypedStatement::Condition(
+                self.statements.push(TypedStatement::Assertion(
                     (0..size)
                         .map(|index| {
                             BooleanExpression::FieldEq(
@@ -53,7 +53,6 @@ impl<'ast, T: Field> VariableAccessRemover<'ast, T> {
                         })
                         .unwrap()
                         .into(),
-                    BooleanExpression::Value(true).into(),
                 ));
 
                 (0..size)
@@ -170,7 +169,7 @@ mod tests {
         assert_eq!(
             VariableAccessRemover::new().fold_statement(access),
             vec![
-                TypedStatement::Condition(
+                TypedStatement::Assertion(
                     BooleanExpression::Or(
                         box BooleanExpression::FieldEq(
                             box FieldElementExpression::Identifier("i".into()),
@@ -182,7 +181,6 @@ mod tests {
                         )
                     )
                     .into(),
-                    BooleanExpression::Value(true).into()
                 ),
                 TypedStatement::Definition(
                     TypedAssignee::Identifier(Variable::field_element("b")),
diff --git a/zokrates_core/src/typed_absy/folder.rs b/zokrates_core/src/typed_absy/folder.rs
index f83244fa..385c4dce 100644
--- a/zokrates_core/src/typed_absy/folder.rs
+++ b/zokrates_core/src/typed_absy/folder.rs
@@ -165,9 +165,7 @@ pub fn fold_statement<'ast, T: Field, F: Folder<'ast, T>>(
             TypedStatement::Definition(f.fold_assignee(a), f.fold_expression(e))
         }
         TypedStatement::Declaration(v) => TypedStatement::Declaration(f.fold_variable(v)),
-        TypedStatement::Condition(left, right) => {
-            TypedStatement::Condition(f.fold_expression(left), f.fold_expression(right))
-        }
+        TypedStatement::Assertion(e) => TypedStatement::Assertion(f.fold_boolean_expression(e)),
         TypedStatement::For(v, from, to, statements) => TypedStatement::For(
             f.fold_variable(v),
             from,
@@ -325,6 +323,21 @@ pub fn fold_boolean_expression<'ast, T: Field, F: Folder<'ast, T>>(
             let e2 = f.fold_boolean_expression(e2);
             BooleanExpression::BoolEq(box e1, box e2)
         }
+        BooleanExpression::ArrayEq(box e1, box e2) => {
+            let e1 = f.fold_array_expression(e1);
+            let e2 = f.fold_array_expression(e2);
+            BooleanExpression::ArrayEq(box e1, box e2)
+        }
+        BooleanExpression::StructEq(box e1, box e2) => {
+            let e1 = f.fold_struct_expression(e1);
+            let e2 = f.fold_struct_expression(e2);
+            BooleanExpression::StructEq(box e1, box e2)
+        }
+        BooleanExpression::UintEq(box e1, box e2) => {
+            let e1 = f.fold_uint_expression(e1);
+            let e2 = f.fold_uint_expression(e2);
+            BooleanExpression::UintEq(box e1, box e2)
+        }
         BooleanExpression::Lt(box e1, box e2) => {
             let e1 = f.fold_field_expression(e1);
             let e2 = f.fold_field_expression(e2);
diff --git a/zokrates_core/src/typed_absy/mod.rs b/zokrates_core/src/typed_absy/mod.rs
index 08d49340..62eb95e6 100644
--- a/zokrates_core/src/typed_absy/mod.rs
+++ b/zokrates_core/src/typed_absy/mod.rs
@@ -300,7 +300,7 @@ pub enum TypedStatement<'ast, T> {
     Return(Vec<TypedExpression<'ast, T>>),
     Definition(TypedAssignee<'ast, T>, TypedExpression<'ast, T>),
     Declaration(Variable<'ast>),
-    Condition(TypedExpression<'ast, T>, TypedExpression<'ast, T>),
+    Assertion(BooleanExpression<'ast, T>),
     For(
         Variable<'ast>,
         FieldElementExpression<'ast, T>,
@@ -327,9 +327,7 @@ impl<'ast, T: fmt::Debug> fmt::Debug for TypedStatement<'ast, T> {
             TypedStatement::Definition(ref lhs, ref rhs) => {
                 write!(f, "Definition({:?}, {:?})", lhs, rhs)
             }
-            TypedStatement::Condition(ref lhs, ref rhs) => {
-                write!(f, "Condition({:?}, {:?})", lhs, rhs)
-            }
+            TypedStatement::Assertion(ref e) => write!(f, "Assertion({:?})", e),
             TypedStatement::For(ref var, ref start, ref stop, ref list) => {
                 write!(f, "for {:?} in {:?}..{:?} do\n", var, start, stop)?;
                 for l in list {
@@ -376,7 +374,7 @@ impl<'ast, T: fmt::Display> fmt::Display for TypedStatement<'ast, T> {
             }
             TypedStatement::Declaration(ref var) => write!(f, "{}", var),
             TypedStatement::Definition(ref lhs, ref rhs) => write!(f, "{} = {}", lhs, rhs),
-            TypedStatement::Condition(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
+            TypedStatement::Assertion(ref e) => write!(f, "assert({})", e),
             TypedStatement::For(ref var, ref start, ref stop, ref list) => {
                 write!(f, "for {} in {}..{} do\n", var, start, stop)?;
                 for l in list {
@@ -639,6 +637,12 @@ pub enum BooleanExpression<'ast, T> {
         Box<BooleanExpression<'ast, T>>,
         Box<BooleanExpression<'ast, T>>,
     ),
+    ArrayEq(Box<ArrayExpression<'ast, T>>, Box<ArrayExpression<'ast, T>>),
+    StructEq(
+        Box<StructExpression<'ast, T>>,
+        Box<StructExpression<'ast, T>>,
+    ),
+    UintEq(Box<UExpression<'ast, T>>, Box<UExpression<'ast, T>>),
     Ge(
         Box<FieldElementExpression<'ast, T>>,
         Box<FieldElementExpression<'ast, T>>,
@@ -906,6 +910,9 @@ impl<'ast, T: fmt::Display> fmt::Display for BooleanExpression<'ast, T> {
             BooleanExpression::Le(ref lhs, ref rhs) => write!(f, "{} <= {}", lhs, rhs),
             BooleanExpression::FieldEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
             BooleanExpression::BoolEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
+            BooleanExpression::ArrayEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
+            BooleanExpression::StructEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
+            BooleanExpression::UintEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
             BooleanExpression::Ge(ref lhs, ref rhs) => write!(f, "{} >= {}", lhs, rhs),
             BooleanExpression::Gt(ref lhs, ref rhs) => write!(f, "{} > {}", lhs, rhs),
             BooleanExpression::Or(ref lhs, ref rhs) => write!(f, "{} || {}", lhs, rhs),
@@ -985,6 +992,15 @@ impl<'ast, T: fmt::Debug> fmt::Debug for BooleanExpression<'ast, T> {
             BooleanExpression::BoolEq(ref lhs, ref rhs) => {
                 write!(f, "BoolEq({:?}, {:?})", lhs, rhs)
             }
+            BooleanExpression::ArrayEq(ref lhs, ref rhs) => {
+                write!(f, "ArrayEq({:?}, {:?})", lhs, rhs)
+            }
+            BooleanExpression::StructEq(ref lhs, ref rhs) => {
+                write!(f, "StructEq({:?}, {:?})", lhs, rhs)
+            }
+            BooleanExpression::UintEq(ref lhs, ref rhs) => {
+                write!(f, "UintEq({:?}, {:?})", lhs, rhs)
+            }
             BooleanExpression::Ge(ref lhs, ref rhs) => write!(f, "Ge({:?}, {:?})", lhs, rhs),
             BooleanExpression::Gt(ref lhs, ref rhs) => write!(f, "Gt({:?}, {:?})", lhs, rhs),
             BooleanExpression::And(ref lhs, ref rhs) => write!(f, "And({:?}, {:?})", lhs, rhs),
diff --git a/zokrates_core/src/zir/folder.rs b/zokrates_core/src/zir/folder.rs
index af29c188..71039a30 100644
--- a/zokrates_core/src/zir/folder.rs
+++ b/zokrates_core/src/zir/folder.rs
@@ -130,9 +130,7 @@ pub fn fold_statement<'ast, T: Field, F: Folder<'ast, T>>(
             ZirStatement::Definition(f.fold_assignee(a), f.fold_expression(e))
         }
         ZirStatement::Declaration(v) => ZirStatement::Declaration(f.fold_variable(v)),
-        ZirStatement::Condition(left, right) => {
-            ZirStatement::Condition(f.fold_expression(left), f.fold_expression(right))
-        }
+        ZirStatement::Assertion(e) => ZirStatement::Assertion(f.fold_boolean_expression(e)),
         ZirStatement::MultipleDefinition(variables, elist) => ZirStatement::MultipleDefinition(
             variables.into_iter().map(|v| f.fold_variable(v)).collect(),
             f.fold_expression_list(elist),
@@ -201,6 +199,11 @@ pub fn fold_boolean_expression<'ast, T: Field, F: Folder<'ast, T>>(
             let e2 = f.fold_boolean_expression(e2);
             BooleanExpression::BoolEq(box e1, box e2)
         }
+        BooleanExpression::UintEq(box e1, box e2) => {
+            let e1 = f.fold_uint_expression(e1);
+            let e2 = f.fold_uint_expression(e2);
+            BooleanExpression::UintEq(box e1, box e2)
+        }
         BooleanExpression::Lt(box e1, box e2) => {
             let e1 = f.fold_field_expression(e1);
             let e2 = f.fold_field_expression(e2);
diff --git a/zokrates_core/src/zir/mod.rs b/zokrates_core/src/zir/mod.rs
index bd2bbbf2..e95f7687 100644
--- a/zokrates_core/src/zir/mod.rs
+++ b/zokrates_core/src/zir/mod.rs
@@ -191,7 +191,7 @@ pub enum ZirStatement<'ast, T> {
     Return(Vec<ZirExpression<'ast, T>>),
     Definition(ZirAssignee<'ast>, ZirExpression<'ast, T>),
     Declaration(Variable<'ast>),
-    Condition(ZirExpression<'ast, T>, ZirExpression<'ast, T>),
+    Assertion(BooleanExpression<'ast, T>),
     MultipleDefinition(Vec<Variable<'ast>>, ZirExpressionList<'ast, T>),
 }
 
@@ -212,9 +212,7 @@ impl<'ast, T: fmt::Debug> fmt::Debug for ZirStatement<'ast, T> {
             ZirStatement::Definition(ref lhs, ref rhs) => {
                 write!(f, "Definition({:?}, {:?})", lhs, rhs)
             }
-            ZirStatement::Condition(ref lhs, ref rhs) => {
-                write!(f, "Condition({:?}, {:?})", lhs, rhs)
-            }
+            ZirStatement::Assertion(ref e) => write!(f, "Assertion({:?})", e),
             ZirStatement::MultipleDefinition(ref lhs, ref rhs) => {
                 write!(f, "MultipleDefinition({:?}, {:?})", lhs, rhs)
             }
@@ -235,9 +233,9 @@ impl<'ast, T: fmt::Display> fmt::Display for ZirStatement<'ast, T> {
                 }
                 write!(f, "")
             }
-            ZirStatement::Declaration(ref var) => write!(f, "{}", var),
+            ZirStatement::Declaration(ref var) => write!(f, "assert({})", var),
             ZirStatement::Definition(ref lhs, ref rhs) => write!(f, "{} = {}", lhs, rhs),
-            ZirStatement::Condition(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
+            ZirStatement::Assertion(ref e) => write!(f, "{}", e),
             ZirStatement::MultipleDefinition(ref ids, ref rhs) => {
                 for (i, id) in ids.iter().enumerate() {
                     write!(f, "{}", id)?;
@@ -399,6 +397,7 @@ pub enum BooleanExpression<'ast, T> {
         Box<BooleanExpression<'ast, T>>,
         Box<BooleanExpression<'ast, T>>,
     ),
+    UintEq(Box<UExpression<'ast, T>>, Box<UExpression<'ast, T>>),
     Ge(
         Box<FieldElementExpression<'ast, T>>,
         Box<FieldElementExpression<'ast, T>>,
@@ -511,6 +510,7 @@ impl<'ast, T: fmt::Display> fmt::Display for BooleanExpression<'ast, T> {
             BooleanExpression::Le(ref lhs, ref rhs) => write!(f, "{} <= {}", lhs, rhs),
             BooleanExpression::FieldEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
             BooleanExpression::BoolEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
+            BooleanExpression::UintEq(ref lhs, ref rhs) => write!(f, "{} == {}", lhs, rhs),
             BooleanExpression::Ge(ref lhs, ref rhs) => write!(f, "{} >= {}", lhs, rhs),
             BooleanExpression::Gt(ref lhs, ref rhs) => write!(f, "{} > {}", lhs, rhs),
             BooleanExpression::Or(ref lhs, ref rhs) => write!(f, "{} || {}", lhs, rhs),
diff --git a/zokrates_core/tests/out_of_range.rs b/zokrates_core/tests/out_of_range.rs
index 571eb571..0f8ab9d8 100644
--- a/zokrates_core/tests/out_of_range.rs
+++ b/zokrates_core/tests/out_of_range.rs
@@ -15,7 +15,7 @@ fn out_of_range() {
     let source = r#"
 		def main(private field a) -> (field):
 	        field x = if a < 5555 then 3333 else 4444 fi
-	        x == 3333
+	        assert(x == 3333)
 			return 1
 	"#
     .to_string();
diff --git a/zokrates_core_test/tests/tests/assert_one.zok b/zokrates_core_test/tests/tests/assert_one.zok
index 4e43c87a..1b025194 100644
--- a/zokrates_core_test/tests/tests/assert_one.zok
+++ b/zokrates_core_test/tests/tests/assert_one.zok
@@ -1,3 +1,3 @@
 def main(field a) -> ():
-	a == 1
+	assert(a == 1)
 	return
\ No newline at end of file
diff --git a/zokrates_core_test/tests/tests/memoize/memoize.zok b/zokrates_core_test/tests/tests/memoize/memoize.zok
index e092c80b..fa3d38b3 100644
--- a/zokrates_core_test/tests/tests/memoize/memoize.zok
+++ b/zokrates_core_test/tests/tests/memoize/memoize.zok
@@ -6,9 +6,9 @@ def local(field a) -> (field): // this costs 3 constraints per call
 
 def main(field a) -> ():
 	// calling a local function many times with the same arg should cost only once
-	local(a) + local(a) + local(a) + local(a) + local(a) == 5 * (a ** 8)
+	assert(local(a) + local(a) + local(a) + local(a) + local(a) == 5 * (a ** 8))
 
 	// calling an imported function many times with the same arg should cost only once
-	dep(a) + dep(a) + dep(a) + dep(a) + dep(a) == 5 * (a ** 4)
+	assert(dep(a) + dep(a) + dep(a) + dep(a) + dep(a) == 5 * (a ** 4))
 
 	return
diff --git a/zokrates_core_test/tests/tests/precedence.json b/zokrates_core_test/tests/tests/precedence.json
index 38faa6e1..5cf9609d 100644
--- a/zokrates_core_test/tests/tests/precedence.json
+++ b/zokrates_core_test/tests/tests/precedence.json
@@ -4,15 +4,11 @@
 	"tests": [
         {
             "input": {
-                "values": [
-                    "12"
-                ]
+                "values": []
             },
             "output": {
                 "Ok": {
-                    "values": [
-                        "12"
-                    ]
+                    "values": []
                 }
             }
         }
diff --git a/zokrates_core_test/tests/tests/precedence.zok b/zokrates_core_test/tests/tests/precedence.zok
index 86404b44..e6120517 100644
--- a/zokrates_core_test/tests/tests/precedence.zok
+++ b/zokrates_core_test/tests/tests/precedence.zok
@@ -1,8 +1,8 @@
-def main(field g) -> (field):
-  9 == 1 + 2 * 2 ** 2                                              // Checks precedence of arithmetic operators (expecting transitive behaviour)
-  9 == 2 ** 2 * 2 + 1
-  7 == 2 ** 2 * 2 - 1
-  3 == 2 ** 2 / 2 + 1
+def main() -> ():
+  assert(9 == 1 + 2 * 2 ** 2)                                      // Checks precedence of arithmetic operators (expecting transitive behaviour)
+  assert(9 == 2 ** 2 * 2 + 1)
+  assert(7 == 2 ** 2 * 2 - 1)
+  assert(3 == 2 ** 2 / 2 + 1)
 
   field a = if 3 == 2 ** 2 / 2 + 1 && true then 1 else 0 fi        // combines arithmetic with boolean operators
   field b = if 3 == 3 && 4 < 5 then 1 else 0 fi                    // checks precedence of boolean operators
@@ -11,6 +11,8 @@ def main(field g) -> (field):
   field e = if 2 >= 1 && 4 > 5 || 1 == 1 then 1 else 0 fi
   field f = if 1 < 2 && false || 4 < 5 && 2 >= 1 then 1 else 0 fi
 
+  assert(0x00 ^ 0x00 == 0x00)
+
   //check if all statements have evalutated to true
-  a * b * c * d * e * f == 1
-  return g
+  assert(a * b * c * d * e * f == 1)
+  return
diff --git a/zokrates_core_test/tests/tests/uint/eq.json b/zokrates_core_test/tests/tests/uint/eq.json
new file mode 100644
index 00000000..9c1e9c7e
--- /dev/null
+++ b/zokrates_core_test/tests/tests/uint/eq.json
@@ -0,0 +1,4 @@
+{
+	"entry_point": "./tests/tests/uint/eq.zok",
+	"tests": []
+}
\ No newline at end of file
diff --git a/zokrates_core_test/tests/tests/uint/eq.zok b/zokrates_core_test/tests/tests/uint/eq.zok
new file mode 100644
index 00000000..07eadf24
--- /dev/null
+++ b/zokrates_core_test/tests/tests/uint/eq.zok
@@ -0,0 +1,3 @@
+def main(private u32 a, u32 b) -> (field):
+  field result = if a * a == b then 1 else 0 fi
+  return result
\ No newline at end of file
diff --git a/zokrates_core_test/tests/tests/uint/operations.zok b/zokrates_core_test/tests/tests/uint/operations.zok
index 18181b71..4ef034b9 100644
--- a/zokrates_core_test/tests/tests/uint/operations.zok
+++ b/zokrates_core_test/tests/tests/uint/operations.zok
@@ -60,47 +60,47 @@ def main(u32 e, u32 f, u32[4] terms) -> ():
 
 	// rotate
 	u32 rotated = right_rotate_4(e)
-	rotated == 0x81234567
+	assert(rotated == 0x81234567)
 
 	// and
-	(e & f) == 0x00204460
+	assert((e & f) == 0x00204460)
 
 	// xor
-	(e ^ f) == 0x1317131f
+	assert((e ^ f) == 0x1317131f)
 
 	// shift
-	e >> 12 == 0x00012345
-	e << 12 == 0x45678000
+	assert(e >> 12 == 0x00012345)
+	assert(e << 12 == 0x45678000)
 
 	// not
-	!e == 0xedcba987
+	assert(!e == 0xedcba987)
 
 	// add
-	terms[0] + terms[1] + terms[2] + terms[3] == 0xddddddda
+	assert(terms[0] + terms[1] + terms[2] + terms[3] == 0xddddddda)
 
 	// to_bits
 	bool[32] bits1 = to_bits(e)
 	bool[32] expected1 = [false, false, false, true, false, false, true, false, false, false, true, true, false, true,  false, false, false, true, false, true, false, true, true, false, false, true, true,  true, true, false, false, false]
-	bits1 == expected1
-	e == from_bits(expected1)
+	assert(bits1 == expected1)
+	assert(e == from_bits(expected1))
 
 	bool[32] bits2 = to_bits(f)
 	bool[32] expected2 = [false, false, false, false, false, false, false, true, false, false, true, false, false, false, true, true, false, true, false, false, false, true,  false, true, false, true, true, false, false, true, true, true]
-	bits2 == expected2
-	f == from_bits(expected2)
+	assert(bits2 == expected2)
+	assert(f == from_bits(expected2))
 
 	// S0
 	u32 e2 = right_rotate_2(e)
 	u32 e13 = right_rotate_13(e)
 	u32 e22 = right_rotate_22(e)
 	u32 S0 = e2 ^ e13 ^ e22
-	S0 == 0x66146474
+	assert(S0 == 0x66146474)
 
 	// S1
 	u32 e6 = right_rotate_6(e)
 	u32 e11 = right_rotate_11(e)
 	u32 e25 = right_rotate_25(e)
 	u32 S1 = e6 ^ e11 ^ e25
-	S1 == 0x3561abda
+	assert(S1 == 0x3561abda)
 
 	return
\ No newline at end of file
diff --git a/zokrates_core_test/tests/tests/uint/propagation/rotate.zok b/zokrates_core_test/tests/tests/uint/propagation/rotate.zok
index a3c4f8e6..a501c0db 100644
--- a/zokrates_core_test/tests/tests/uint/propagation/rotate.zok
+++ b/zokrates_core_test/tests/tests/uint/propagation/rotate.zok
@@ -54,6 +54,7 @@ def right_rotate_22(u32 e) -> (u32):
 def right_rotate_25(u32 e) -> (u32):
 	bool[32] b = to_bits(e)
 	u32 res = from_bits([...b[7..], ...b[..7]])
+
 	return res
 
 def main() -> ():
@@ -62,47 +63,47 @@ def main() -> ():
 
 	// rotate
 	u32 rotated = right_rotate_4(e)
-	rotated == 0x81234567
+	assert(rotated == 0x81234567)
 
 	// and
-	(e & f) == 0x00204460
+	assert((e & f) == 0x00204460)
 
 	// xor
-	(e ^ f) == 0x1317131f
+	assert((e ^ f) == 0x1317131f)
 
 	// shift
-	e >> 12 == 0x00012345
-	e << 12 == 0x45678000
+	assert(e >> 12 == 0x00012345)
+	assert(e << 12 == 0x45678000)
 
 	// not
-	!e == 0xedcba987
+	assert(!e == 0xedcba987)
 
 	// add
-	0xfefefefe + 0xefefefef + 0xffffffff + 0xeeeeeeee == 0xddddddda
+	assert(0xfefefefe + 0xefefefef + 0xffffffff + 0xeeeeeeee == 0xddddddda)
 
 	// to_bits
 	bool[32] bits1 = to_bits(e)
 	bool[32] expected1 = [false, false, false, true, false, false, true, false, false, false, true, true, false, true,  false, false, false, true, false, true, false, true, true, false, false, true, true,  true, true, false, false, false]
-	bits1 == expected1
-	e == from_bits(expected1)
+	assert(bits1 == expected1)
+	assert(e == from_bits(expected1))
 
 	bool[32] bits2 = to_bits(f)
 	bool[32] expected2 = [false, false, false, false, false, false, false, true, false, false, true, false, false, false, true, true, false, true, false, false, false, true,  false, true, false, true, true, false, false, true, true, true]
-	bits2 == expected2
-	f == from_bits(expected2)
+	assert(bits2 == expected2)
+	assert(f == from_bits(expected2))
 
 	// S0
 	u32 e2 = right_rotate_2(e)
 	u32 e13 = right_rotate_13(e)
 	u32 e22 = right_rotate_22(e)
 	u32 S0 = e2 ^ e13 ^ e22
-	S0 == 0x66146474
+	assert(S0 == 0x66146474)
 
 	// S1
 	u32 e6 = right_rotate_6(e)
 	u32 e11 = right_rotate_11(e)
 	u32 e25 = right_rotate_25(e)
 	u32 S1 = e6 ^ e11 ^ e25
-	S1 == 0x3561abda
+	assert(S1 == 0x3561abda)
 
 	return
\ No newline at end of file
diff --git a/zokrates_parser/src/ace_mode/index.js b/zokrates_parser/src/ace_mode/index.js
index b4753e6c..21eb6e82 100644
--- a/zokrates_parser/src/ace_mode/index.js
+++ b/zokrates_parser/src/ace_mode/index.js
@@ -37,7 +37,7 @@ ace.define("ace/mode/zokrates_highlight_rules",["require","exports","module","ac
     var ZoKratesHighlightRules = function () {
 
         var keywords = (
-            "endfor|as|return|byte|field|bool|if|then|fi|do|else|export|false|def|for|import|from|uint|in|public|private|struct|true"
+            "assert|endfor|as|return|byte|field|bool|if|then|fi|do|else|export|false|def|for|import|from|uint|in|public|private|struct|true"
         );
 
         var keywordMapper = this.createKeywordMapper({
diff --git a/zokrates_parser/src/zokrates.pest b/zokrates_parser/src/zokrates.pest
index ba2ea000..a19f915d 100644
--- a/zokrates_parser/src/zokrates.pest
+++ b/zokrates_parser/src/zokrates.pest
@@ -46,7 +46,7 @@ statement = { (return_statement // does not require subsequent newline
 iteration_statement = { "for" ~ ty ~ identifier ~ "in" ~ expression ~ ".." ~ expression ~ "do" ~ NEWLINE* ~ statement* ~ "endfor"}
 return_statement = { "return" ~ expression_list}
 definition_statement = { optionally_typed_assignee_list ~ "=" ~ expression } // declare and assign, so only identifiers are allowed, unlike `assignment_statement`
-expression_statement = {expression}
+expression_statement = {"assert" ~ "(" ~ expression ~ ")"}
 
 optionally_typed_assignee_list = _{ optionally_typed_assignee ~ ("," ~ optionally_typed_assignee)* }
 optionally_typed_assignee = { (ty ~ assignee) | (assignee) } // we don't use { ty? ~ identifier } as with a single token, it gets parsed as `ty` but we want `identifier`
@@ -124,6 +124,8 @@ op_unary = { op_not }
 WHITESPACE = _{ " " | "\t" | "\\" ~ NEWLINE}
 COMMENT = _{ ("/*" ~ (!"*/" ~ ANY)* ~ "*/") | ("//" ~ (!NEWLINE ~ ANY)*) }
 
-keyword = @{"as"|"bool"|"byte"|"def"|"do"|"else"|"endfor"|"export"|"false"|"field"|"for"|"if"|"then"|"fi"|"import"|"from"|
+// the ordering of reserved keywords matters: if "as" is before "assert", then "assert" gets parsed as (as)(sert) and incorrectly
+// accepted
+keyword = @{"assert"|"as"|"bool"|"byte"|"def"|"do"|"else"|"endfor"|"export"|"false"|"field"|"for"|"if"|"then"|"fi"|"import"|"from"|
             "in"|"private"|"public"|"return"|"struct"|"true"|"u8"|"u16"|"u32"
             }
diff --git a/zokrates_pest_ast/src/lib.rs b/zokrates_pest_ast/src/lib.rs
index cba0188a..bdf4e71a 100644
--- a/zokrates_pest_ast/src/lib.rs
+++ b/zokrates_pest_ast/src/lib.rs
@@ -32,21 +32,22 @@ mod ast {
         static ref PREC_CLIMBER: PrecClimber<Rule> = build_precedence_climber();
     }
 
+    // based on https://docs.python.org/3/reference/expressions.html#operator-precedence
     fn build_precedence_climber() -> PrecClimber<Rule> {
         PrecClimber::new(vec![
             Operator::new(Rule::op_or, Assoc::Left),
             Operator::new(Rule::op_and, Assoc::Left),
+            Operator::new(Rule::op_lt, Assoc::Left)
+                | Operator::new(Rule::op_lte, Assoc::Left)
+                | Operator::new(Rule::op_gt, Assoc::Left)
+                | Operator::new(Rule::op_gte, Assoc::Left)
+                | Operator::new(Rule::op_not_equal, Assoc::Left)
+                | Operator::new(Rule::op_equal, Assoc::Left),
             Operator::new(Rule::op_bit_or, Assoc::Left),
             Operator::new(Rule::op_bit_xor, Assoc::Left),
             Operator::new(Rule::op_bit_and, Assoc::Left),
-            Operator::new(Rule::op_equal, Assoc::Left)
-                | Operator::new(Rule::op_not_equal, Assoc::Left),
-            Operator::new(Rule::op_lte, Assoc::Left)
-                | Operator::new(Rule::op_gte, Assoc::Left)
-                | Operator::new(Rule::op_lt, Assoc::Left)
-                | Operator::new(Rule::op_gt, Assoc::Left),
-            Operator::new(Rule::op_right_shift, Assoc::Left)
-                | Operator::new(Rule::op_left_shift, Assoc::Left),
+            Operator::new(Rule::op_left_shift, Assoc::Left)
+                | Operator::new(Rule::op_right_shift, Assoc::Left),
             Operator::new(Rule::op_add, Assoc::Left) | Operator::new(Rule::op_sub, Assoc::Left),
             Operator::new(Rule::op_mul, Assoc::Left) | Operator::new(Rule::op_div, Assoc::Left),
             Operator::new(Rule::op_pow, Assoc::Left),
@@ -1174,9 +1175,9 @@ mod tests {
         field a = 1
         a[32 + x][55] = y
         for field i in 0..3 do
-               a == 1 + 2 + 3+ 4+ 5+ 6+ 6+ 7+ 8 + 4+ 5+ 3+ 4+ 2+ 3
+               assert(a == 1 + 2 + 3+ 4+ 5+ 6+ 6+ 7+ 8 + 4+ 5+ 3+ 4+ 2+ 3)
         endfor
-        a.member == 1
+        assert(a.member == 1)
         return a
 "#;
         let res = generate_ast(&source);
diff --git a/zokrates_stdlib/stdlib/ecc/edwardsOnCurve.zok b/zokrates_stdlib/stdlib/ecc/edwardsOnCurve.zok
index 4d30f933..2fc71e66 100644
--- a/zokrates_stdlib/stdlib/ecc/edwardsOnCurve.zok
+++ b/zokrates_stdlib/stdlib/ecc/edwardsOnCurve.zok
@@ -13,6 +13,6 @@ def main(field[2] pt, BabyJubJubParams context) -> (bool):
     field vv = pt[1] * pt[1]
     field uuvv = uu * vv
 
-    a * uu + vv == 1 + d * uuvv
+    assert(a * uu + vv == 1 + d * uuvv)
 
     return true
diff --git a/zokrates_stdlib/stdlib/ecc/edwardsOrderCheck.zok b/zokrates_stdlib/stdlib/ecc/edwardsOrderCheck.zok
index e85391bf..8df85407 100644
--- a/zokrates_stdlib/stdlib/ecc/edwardsOrderCheck.zok
+++ b/zokrates_stdlib/stdlib/ecc/edwardsOrderCheck.zok
@@ -6,14 +6,14 @@ from "ecc/babyjubjubParams" import BabyJubJubParams
 // Verifies that the point is not one of the low-order points.
 // If any of the points is multiplied by the cofactor, the resulting point
 // will be infinity.
-// Returns 1 if the point is not one of the low-order points, 0 otherwise.
+// Returns true if the point is not one of the low-order points, false otherwise.
 // Curve parameters are defined with the last argument
 // https://github.com/zcash-hackworks/sapling-crypto/blob/master/src/jubjub/edwards.rs#L166
-def main(field[2] pt, BabyJubJubParams context) -> (field):
+def main(field[2] pt, BabyJubJubParams context) -> (bool):
 
     field cofactor = context.JUBJUBC
 
-    cofactor == 8
+    assert(cofactor == 8)
 
     // Co-factor currently hard-coded to 8 for efficiency reasons
     // See discussion here: https://github.com/Zokrates/ZoKrates/pull/301#discussion_r267203391
@@ -24,6 +24,4 @@ def main(field[2] pt, BabyJubJubParams context) -> (field):
     ptExp = add(ptExp, ptExp, context)    // 4*pt
     ptExp = add(ptExp, ptExp, context)    // 8*pt
 
-    field out = if ptExp[0] == 0 && ptExp[1] == 1 then 0 else 1 fi
-
-    return out
+    return !(ptExp[0] == 0 && ptExp[1] == 1)
diff --git a/zokrates_stdlib/stdlib/ecc/edwardsScalarMult.zok b/zokrates_stdlib/stdlib/ecc/edwardsScalarMult.zok
index cd1fd3f3..5c6b7a5c 100644
--- a/zokrates_stdlib/stdlib/ecc/edwardsScalarMult.zok
+++ b/zokrates_stdlib/stdlib/ecc/edwardsScalarMult.zok
@@ -1,5 +1,5 @@
 import "ecc/edwardsAdd" as add
-import "ecc/edwardsOnCurve" as assertOnCurve
+import "ecc/edwardsOnCurve" as onCurve
 from "ecc/babyjubjubParams" import BabyJubJubParams
 
 // Function that implements scalar multiplication for a fixed base point
@@ -22,6 +22,6 @@ def main(bool[256] exponent, field[2] pt, BabyJubJubParams context) -> (field[2]
         doubledP = add(doubledP, doubledP, context)
     endfor
 
-    true == assertOnCurve(accumulatedP, context)
+    assert(onCurve(accumulatedP, context))
 
     return accumulatedP
\ No newline at end of file
diff --git a/zokrates_stdlib/stdlib/ecc/proofOfOwnership.zok b/zokrates_stdlib/stdlib/ecc/proofOfOwnership.zok
index 730f2c5e..7e366ffa 100644
--- a/zokrates_stdlib/stdlib/ecc/proofOfOwnership.zok
+++ b/zokrates_stdlib/stdlib/ecc/proofOfOwnership.zok
@@ -24,6 +24,6 @@ def main(field[2] pk, field sk, BabyJubJubParams context) -> (bool):
     bool[256] skBits = unpack256(sk)
     field[2] ptExp = multiply(skBits, G, context)
 
-    bool out =	ptExp[0] == pk[0] && ptExp[1] == pk[1]
+    bool out = ptExp[0] == pk[0] && ptExp[1] == pk[1]
 
     return out
diff --git a/zokrates_stdlib/stdlib/signatures/verifyEddsa.zok b/zokrates_stdlib/stdlib/signatures/verifyEddsa.zok
index 198511a3..f88231ef 100644
--- a/zokrates_stdlib/stdlib/signatures/verifyEddsa.zok
+++ b/zokrates_stdlib/stdlib/signatures/verifyEddsa.zok
@@ -32,9 +32,8 @@ def main(private field[2] R, private field S, field[2] A, bool[256] M0, bool[256
     field[2] G = [context.Gu, context.Gv]
 
     // Check if R is on curve and if it is not in a small subgroup. A is public input and can be checked offline
-    true == onCurve(R, context) // throws if R is not on curve
-    field isPrimeOrder = orderCheck(R, context)
-    1 == isPrimeOrder	
+    assert(onCurve(R, context)) // throws if R is not on curve
+    assert(orderCheck(R, context))
 
     bool[256] Rx = unpack256(R[0])
     bool[256] Ax = unpack256(A[0])
diff --git a/zokrates_stdlib/stdlib/utils/pack/unpack128.zok b/zokrates_stdlib/stdlib/utils/pack/unpack128.zok
index 7d3a3ce2..6a7eb5b4 100644
--- a/zokrates_stdlib/stdlib/utils/pack/unpack128.zok
+++ b/zokrates_stdlib/stdlib/utils/pack/unpack128.zok
@@ -6,6 +6,6 @@ def main(field i) -> (bool[128]):
 
     bool[254] b = unpack(i)
 
-    b[0..126] == [false; 126]
+    assert(b[0..126] == [false; 126])
 
     return b[126..254]
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsAdd.json b/zokrates_stdlib/tests/tests/ecc/edwardsAdd.json
index 0075440a..2ff3bf0a 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsAdd.json
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsAdd.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsAdd.zok b/zokrates_stdlib/tests/tests/ecc/edwardsAdd.zok
index 48866390..9d3fe6b3 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsAdd.zok
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsAdd.zok
@@ -5,34 +5,34 @@ from "ecc/babyjubjubParams" import BabyJubJubParams
 
 // Code to create test cases:
 // https://github.com/Zokrates/pycrypto
-def testDoubleViaAdd() -> (field):
+def testDoubleViaAdd() -> (bool):
 	BabyJubJubParams context = context()
 	field[2] G = [context.Gu, context.Gv]
 	
 	field[2] out = add(G, G, context)
 
-	out[0] == 17324563846726889236817837922625232543153115346355010501047597319863650987830
-	out[1] == 20022170825455209233733649024450576091402881793145646502279487074566492066831
+	assert(out[0] == 17324563846726889236817837922625232543153115346355010501047597319863650987830)
+	assert(out[1] == 20022170825455209233733649024450576091402881793145646502279487074566492066831)
 
-	return 1
+	return true
 
-def testIdentities() -> (field):
+def testIdentities() -> (bool):
 	BabyJubJubParams context = context()
 	field[2] G = [context.Gu, context.Gv]
 	field[2] inf = context.INFINITY
 
-	G == add(G, inf, context)
+	assert(G == add(G, inf, context))
 	
 	field[2] nG = neg(G)
 	field[2] nGaddG = add(G, nG, context)
 
-	inf == nGaddG
+	assert(inf == nGaddG)
 
-	return 1
+	return true
 
-def main() -> (field):
+def main() -> ():
 
-	1 == testDoubleViaAdd()
-	1 == testIdentities()
+	assert(testDoubleViaAdd())
+	assert(testIdentities())
 
-return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsCompress.json b/zokrates_stdlib/tests/tests/ecc/edwardsCompress.json
index f0a5e6e3..53f4fbf6 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsCompress.json
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsCompress.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsCompress.zok b/zokrates_stdlib/tests/tests/ecc/edwardsCompress.zok
index c13e36d5..be2d054f 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsCompress.zok
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsCompress.zok
@@ -4,7 +4,7 @@ from "ecc/babyjubjubParams" import BabyJubJubParams
 
 // Code to create test cases:
 // https://github.com/Zokrates/pycrypto
-def testCompress() -> (field):
+def testCompress() -> (bool):
 	BabyJubJubParams context = context()
 
 	field Gu = context.Gu
@@ -12,12 +12,12 @@ def testCompress() -> (field):
 
 	bool[256] Gcompressed = edwardsCompress([Gu, Gv])
 
-	Gcompressed == [true, false, true, false, true, true, true, false, false, false, false, false, false, true, true, true, false, false, true, false, true, false, false, true, false, true, true, true, true, true, true, true, true, false, false, false, true, true, false, true, false, false, true, true, true, true, false, false, false, false, true, true, true, true, false, true, false, true, true, true, true, false, false, false, false, false, false, true, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, true, true, true, true, true, true, true, false, true, false, false, true, false, false, true, false, false, true, true, false, false, false, false, true, true, false, true, false, true, false, true, false, true, true, false, false, false, false, false, true, true, true, true, true, true, true, false, false, true, true, false, true, false, true, false, false, true, true, true, false, true, false, true, false, false, true, true, true, false, true, true, false, true, false, false, false, false, true, true, false, false, true, false, true, true, false, false, false, false, true, true, false, false, false, false, false, true, true, true, false, true, false, false, false, true, false, false, true, true, false, true, false, false, true, false, false, false, true, true, false, true, true, true, false, true, true, false, false, false, true, true, true, true, false, true, true, true, true, true, true, true, true, false, false, true, true, false, false, true, false, false, false, true, false, true, false, true, false, false, true, false, true, true, false, true, false, true, true, true]
+	assert(Gcompressed == [true, false, true, false, true, true, true, false, false, false, false, false, false, true, true, true, false, false, true, false, true, false, false, true, false, true, true, true, true, true, true, true, true, false, false, false, true, true, false, true, false, false, true, true, true, true, false, false, false, false, true, true, true, true, false, true, false, true, true, true, true, false, false, false, false, false, false, true, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, true, true, true, true, true, true, true, false, true, false, false, true, false, false, true, false, false, true, true, false, false, false, false, true, true, false, true, false, true, false, true, false, true, true, false, false, false, false, false, true, true, true, true, true, true, true, false, false, true, true, false, true, false, true, false, false, true, true, true, false, true, false, true, false, false, true, true, true, false, true, true, false, true, false, false, false, false, true, true, false, false, true, false, true, true, false, false, false, false, true, true, false, false, false, false, false, true, true, true, false, true, false, false, false, true, false, false, true, true, false, true, false, false, true, false, false, false, true, true, false, true, true, true, false, true, true, false, false, false, true, true, true, true, false, true, true, true, true, true, true, true, true, false, false, true, true, false, false, true, false, false, false, true, false, true, false, true, false, false, true, false, true, true, false, true, false, true, true, true])
 
-	return 1
+	return true
 
-def main() -> (field):
+def main() -> ():
 
-	1 == testCompress()
+	assert(testCompress())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.json b/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.json
index 72f134a3..ec61ed51 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.json
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.zok b/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.zok
index 634127cc..e25c0415 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.zok
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsOnCurve.zok
@@ -4,19 +4,19 @@ import "ecc/edwardsOnCurve" as onCurve
 
 // Code to create test cases:
 // https://github.com/Zokrates/pycrypto
-def testOnCurveTrue() -> (field):
+def testOnCurveTrue() -> (bool):
 	BabyJubJubParams context = context()
 
 	field testU = 17324563846726889236817837922625232543153115346355010501047597319863650987830
 	field testV = 20022170825455209233733649024450576091402881793145646502279487074566492066831
 
-	true == onCurve([testU, testV], context)
+	assert(onCurve([testU, testV], context))
 	
-	return 1
+	return true
 
-def main() -> (field):
+def main() -> ():
 
-	1 == testOnCurveTrue()
+	assert(testOnCurveTrue())
 	// onCurve throws for false
 
-	return 1
+	return
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.json b/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.json
index bb221950..07768ffc 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.json
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.zok b/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.zok
index eb0ca612..aa98d2c6 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.zok
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsOrderCheck.zok
@@ -4,31 +4,31 @@ from "ecc/babyjubjubParams" import BabyJubJubParams
 
 // Code to create test cases:
 // https://github.com/Zokrates/pycrypto
-def testOrderCheckTrue() -> (field):
+def testOrderCheckTrue() -> (bool):
 	BabyJubJubParams context = context()
 
 	field testU = 17324563846726889236817837922625232543153115346355010501047597319863650987830
 	field testV = 20022170825455209233733649024450576091402881793145646502279487074566492066831
 
-	field out = orderCheck([testU, testV], context)
-	out == 1
+	bool out = orderCheck([testU, testV], context)
+	assert(out)
 
-	return 1
+	return true
 
-def testOrderCheckFalse() -> (field):
+def testOrderCheckFalse() -> (bool):
 	BabyJubJubParams context = context()
 
 	field testU = 4342719913949491028786768530115087822524712248835451589697801404893164183326
 	field testV = 4826523245007015323400664741523384119579596407052839571721035538011798951543
 
-	field out = orderCheck([testU, testV], context)
-	out == 0
+	bool out = orderCheck([testU, testV], context)
+	assert(!out)
 
-	return 1
+	return true
 
-def main() -> (field):
+def main() -> ():
 
-	1 == testOrderCheckFalse()
-	1 == testOrderCheckTrue()
+	assert(testOrderCheckFalse())
+	assert(testOrderCheckTrue())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.json b/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.json
index a9873c76..f2743f66 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.json
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.zok b/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.zok
index 8fa9415b..93c42a55 100644
--- a/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.zok
+++ b/zokrates_stdlib/tests/tests/ecc/edwardsScalarMult.zok
@@ -4,7 +4,7 @@ import "ecc/edwardsScalarMult" as mul
 
 // Code to create test cases:
 // https://github.com/Zokrates/pycrypto
-def testCyclic() -> (field):
+def testCyclic() -> (bool):
 	BabyJubJubParams context = context()
 	field[2] G = [context.Gu, context.Gv]
 
@@ -13,11 +13,11 @@ def testCyclic() -> (field):
 
 	field[2] out = mul(exp, G, context)
 	
-	G == out
+	assert(G == out)
 	
-	return 1
+	return true
 
-def testMul2() -> (field):
+def testMul2() -> (bool):
 	BabyJubJubParams context = context()
 	field[2] G = [context.Gu, context.Gv]
 	
@@ -25,12 +25,12 @@ def testMul2() -> (field):
 	bool[256] exp = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false]
 	field[2] out = mul(exp, G, context)
 	
-	out[0] == 17324563846726889236817837922625232543153115346355010501047597319863650987830
-	out[1] == 20022170825455209233733649024450576091402881793145646502279487074566492066831
+	assert(out[0] == 17324563846726889236817837922625232543153115346355010501047597319863650987830)
+	assert(out[1] == 20022170825455209233733649024450576091402881793145646502279487074566492066831)
 
-	return 1
+	return true
 
-def testAssociativity() -> (field):
+def testAssociativity() -> (bool):
 	BabyJubJubParams context = context()
 	field[2] G = [context.Gu, context.Gv]
 
@@ -55,13 +55,13 @@ def testAssociativity() -> (field):
 	field[2] Gca = mul(a, Gc, context)
 	field[2] Gcab = mul(b, Gca, context)
 	
-	Gabc == Gbca
-	Gbca == Gcab
-	Gabc == Gcab
+	assert(Gabc == Gbca)
+	assert(Gbca == Gcab)
+	assert(Gabc == Gcab)
 
-	return 1
+	return true
 
-def testMultiplicative() -> (field):
+def testMultiplicative() -> (bool):
 	BabyJubJubParams context = context()
 	field[2] G = [context.Gu, context.Gv]
 
@@ -81,16 +81,16 @@ def testMultiplicative() -> (field):
 
 	field[2] Gmab = mul(ab, G, context)
 
-	Gab == Gba
-	Gba == Gmab
-	Gab == Gmab
+	assert(Gab == Gba)
+	assert(Gba == Gmab)
+	assert(Gab == Gmab)
 
-	return 1
+	return true
 	
-def main() -> (field):
-	1 == testMul2()
-	1 == testCyclic()
-	1 == testAssociativity()
-	1 == testMultiplicative()
+def main() -> ():
+	assert(testMul2())
+	assert(testCyclic())
+	assert(testAssociativity())
+	assert(testMultiplicative())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.json b/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.json
index 0519fc03..779793e5 100644
--- a/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.json
+++ b/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.zok b/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.zok
index 3be541c1..8c26cbbb 100644
--- a/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.zok
+++ b/zokrates_stdlib/tests/tests/ecc/proofOfOwnership.zok
@@ -6,7 +6,7 @@ import "utils/pack/nonStrictUnpack256" as unpack256
 
 // Code to create test cases:
 // https://github.com/Zokrates/pycrypto
-def testOwnershipTrue() -> (field):
+def testOwnershipTrue() -> (bool):
 	BabyJubJubParams context = context()
 	field[2] G = [context.Gu, context.Gv]
 
@@ -15,22 +15,22 @@ def testOwnershipTrue() -> (field):
 
 	bool out = proofOfOwnership(Pk, sk, context)
 
-	out == true
-	return 1
+	assert(out)
+	return true
 
-def testtOwnershipFalse() -> (field):
+def testtOwnershipFalse() -> (bool):
 	BabyJubJubParams context = context()
 
 	field[2] Pk = [16328093915569409528980874702678312730273137210288183490878184636452430630129, 9377227749598842756429258362864743065769435972445705966557343775367597326529]
 	field sk = 1997011358982923168928344992199991480689546837621580239342656433234255379025
 	bool out = proofOfOwnership(Pk, sk, context)
 
-	out == false
-	return 1
+	assert(!out)
+	return true
 
-def main() -> (field):
+def main() -> ():
 
-	1 == testOwnershipTrue()
-	1 == testtOwnershipFalse()
+	assert(testOwnershipTrue())
+	assert(testtOwnershipFalse())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.json b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.json
index dd3d824d..b37df2d6 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.json
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.json
@@ -7,9 +7,7 @@
             },
             "output": {
                 "Ok": {
-                    "values": [
-                        "1"
-                    ]
+                    "values": []
                 }
             }
         }
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.zok b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.zok
index bd2c2a5e..c1f686b8 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.zok
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R10.zok
@@ -1,9 +1,9 @@
 import "hashes/mimc7/mimc7R10"
 
-def main() -> (field):
-	mimc7R10(0, 0) == 6004544488495356385698286530147974336054653445122716140990101827963729149289
-	mimc7R10(100, 0) == 2977550761518141183167168643824354554080911485709001361112529600968315693145
-	mimc7R10(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 2977550761518141183167168643824354554080911485709001361112529600968315693145
-	mimc7R10(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 11476724043755138071320043459606423473319855817296339514744600646762741571430
-	mimc7R10(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 6004544488495356385698286530147974336054653445122716140990101827963729149289
-	return 1
\ No newline at end of file
+def main() -> ():
+	assert(mimc7R10(0, 0) == 6004544488495356385698286530147974336054653445122716140990101827963729149289)
+	assert(mimc7R10(100, 0) == 2977550761518141183167168643824354554080911485709001361112529600968315693145)
+	assert(mimc7R10(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 2977550761518141183167168643824354554080911485709001361112529600968315693145)
+	assert(mimc7R10(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 11476724043755138071320043459606423473319855817296339514744600646762741571430)
+	assert(mimc7R10(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 6004544488495356385698286530147974336054653445122716140990101827963729149289)
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.json b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.json
index 62eef0bd..d5b121ba 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.json
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.json
@@ -7,9 +7,7 @@
             },
             "output": {
                 "Ok": {
-                    "values": [
-                        "1"
-                    ]
+                    "values": []
                 }
             }
         }
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.zok b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.zok
index dea4c87d..9e2047d1 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.zok
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R20.zok
@@ -1,9 +1,9 @@
 import "hashes/mimc7/mimc7R20"
 
-def main() -> (field):
-	mimc7R20(0, 0) == 19139739902058628561064841933381604453445216873412991992755775746150759284829
-	mimc7R20(100, 0) == 8623418512398828792274158979964869393034224267928014534933203776818702139758
-	mimc7R20(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 8623418512398828792274158979964869393034224267928014534933203776818702139758
-	mimc7R20(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 15315177265066649795408805007175121550344555424263995530745989936206840798041
-	mimc7R20(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 19139739902058628561064841933381604453445216873412991992755775746150759284829
-	return 1
\ No newline at end of file
+def main() -> ():
+	assert(mimc7R20(0, 0) == 19139739902058628561064841933381604453445216873412991992755775746150759284829)
+	assert(mimc7R20(100, 0) == 8623418512398828792274158979964869393034224267928014534933203776818702139758)
+	assert(mimc7R20(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 8623418512398828792274158979964869393034224267928014534933203776818702139758)
+	assert(mimc7R20(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 15315177265066649795408805007175121550344555424263995530745989936206840798041)
+	assert(mimc7R20(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 19139739902058628561064841933381604453445216873412991992755775746150759284829)
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.json b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.json
index 84919fff..37933e80 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.json
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.json
@@ -7,9 +7,7 @@
             },
             "output": {
                 "Ok": {
-                    "values": [
-                        "1"
-                    ]
+                    "values": []
                 }
             }
         }
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.zok b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.zok
index b799d34e..6c25fc3a 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.zok
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R50.zok
@@ -1,9 +1,9 @@
 import "hashes/mimc7/mimc7R50"
 
-def main() -> (field):
-	mimc7R50(0, 0) == 3049953358280347916081509186284461274525472221619157672645224540758481713173
-	mimc7R50(100, 0) == 18511388995652647480418174218630545482006454713617579894396683237092568946789
-	mimc7R50(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 18511388995652647480418174218630545482006454713617579894396683237092568946789
-	mimc7R50(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 9149577627043020462780389988155990926223727917856424056384664564191878439702
-	mimc7R50(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 3049953358280347916081509186284461274525472221619157672645224540758481713173
-	return 1
\ No newline at end of file
+def main() -> ():
+	assert(mimc7R50(0, 0) == 3049953358280347916081509186284461274525472221619157672645224540758481713173)
+	assert(mimc7R50(100, 0) == 18511388995652647480418174218630545482006454713617579894396683237092568946789)
+	assert(mimc7R50(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 18511388995652647480418174218630545482006454713617579894396683237092568946789)
+	assert(mimc7R50(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 9149577627043020462780389988155990926223727917856424056384664564191878439702)
+	assert(mimc7R50(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 3049953358280347916081509186284461274525472221619157672645224540758481713173)
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.json b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.json
index b3c2b8a5..b5c304e0 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.json
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.json
@@ -7,9 +7,7 @@
             },
             "output": {
                 "Ok": {
-                    "values": [
-                        "1"
-                    ]
+                    "values": []
                 }
             }
         }
diff --git a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.zok b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.zok
index 45d6ea9a..0fcceeb7 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.zok
+++ b/zokrates_stdlib/tests/tests/hashes/mimc7/mimc7R90.zok
@@ -1,9 +1,9 @@
 import "hashes/mimc7/mimc7R90"
 
-def main() -> (field):
-	mimc7R90(0, 0) == 20281265111705407344053532742843085357648991805359414661661476832595822221514
-	mimc7R90(100, 0) == 1010054095264022068840870550831559811104631937745987065544478027572003292636
-	mimc7R90(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 1010054095264022068840870550831559811104631937745987065544478027572003292636
-	mimc7R90(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 8189519586469873426687580455476035992041353456517724932462363814215190642760
-	mimc7R90(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 20281265111705407344053532742843085357648991805359414661661476832595822221514
-	return 1
\ No newline at end of file
+def main() -> ():
+	assert(mimc7R90(0, 0) == 20281265111705407344053532742843085357648991805359414661661476832595822221514)
+	assert(mimc7R90(100, 0) == 1010054095264022068840870550831559811104631937745987065544478027572003292636)
+	assert(mimc7R90(100, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 1010054095264022068840870550831559811104631937745987065544478027572003292636)
+	assert(mimc7R90(21888242871839275222246405745257275088548364400416034343698204186575808495618, 1) == 8189519586469873426687580455476035992041353456517724932462363814215190642760)
+	assert(mimc7R90(21888242871839275222246405745257275088548364400416034343698204186575808495617, 21888242871839275222246405745257275088548364400416034343698204186575808495617) == 20281265111705407344053532742843085357648991805359414661661476832595822221514)
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.json b/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.json
index dedd1b67..98b62d1d 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.json
+++ b/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.json
@@ -7,9 +7,7 @@
             },
             "output": {
                 "Ok": {
-                    "values": [
-                        "1"
-                    ]
+                    "values": []
                 }
             }
         }
diff --git a/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.zok b/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.zok
index 9c24b9a6..5785ecee 100644
--- a/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.zok
+++ b/zokrates_stdlib/tests/tests/hashes/mimcSponge/mimcSponge.zok
@@ -1,7 +1,7 @@
 import "hashes/mimcSponge/mimcSponge" as mimcSponge
 
-def main() -> (field):
-	mimcSponge([1,2], 3) == [20225509322021146255705869525264566735642015554514977326536820959638320229084,13871743498877225461925335509899475799121918157213219438898506786048812913771,21633608428713573518356618235457250173701815120501233429160399974209848779097]
-	mimcSponge([0,0], 0) == [20636625426020718969131298365984859231982649550971729229988535915544421356929,6046202021237334713296073963481784771443313518730771623154467767602059802325,16227963524034219233279650312501310147918176407385833422019760797222680144279]
-	mimcSponge([21888242871839275222246405745257275088548364400416034343698204186575808495617, 0], 0) == [20636625426020718969131298365984859231982649550971729229988535915544421356929,6046202021237334713296073963481784771443313518730771623154467767602059802325,16227963524034219233279650312501310147918176407385833422019760797222680144279]
-	return 1
\ No newline at end of file
+def main() -> ():
+	assert(mimcSponge([1,2], 3) == [20225509322021146255705869525264566735642015554514977326536820959638320229084,13871743498877225461925335509899475799121918157213219438898506786048812913771,21633608428713573518356618235457250173701815120501233429160399974209848779097])
+	assert(mimcSponge([0,0], 0) == [20636625426020718969131298365984859231982649550971729229988535915544421356929,6046202021237334713296073963481784771443313518730771623154467767602059802325,16227963524034219233279650312501310147918176407385833422019760797222680144279])
+	assert(mimcSponge([21888242871839275222246405745257275088548364400416034343698204186575808495617, 0], 0) == [20636625426020718969131298365984859231982649550971729229988535915544421356929,6046202021237334713296073963481784771443313518730771623154467767602059802325,16227963524034219233279650312501310147918176407385833422019760797222680144279])
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.json b/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.json
index 6ae7f7e1..79c4aeb1 100644
--- a/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.json
+++ b/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.zok b/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.zok
index 9e281330..d778971d 100644
--- a/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.zok
+++ b/zokrates_stdlib/tests/tests/hashes/pedersen/512bit.zok
@@ -14,12 +14,12 @@
 
 import "hashes/pedersen/512bit" as pedersen
 
-def main() -> (field):
+def main() -> ():
 	
 	bool[512] e = [false, false, false, true, false, true, true, true, true, true, false, true, false, false, true, false, true, true, true, false, false, true, true, false, true, true, false, true, true, false, false, true, false, true, false, true, true, true, false, false, false, true, true, true, false, true, false, false, true, true, true, false, true, false, false, true, false, true, true, true, true, true, false, false, false, true, false, false, true, false, true, true, true, true, true, true, false, true, true, false, false, false, false, false, true, true, false, false, true, true, false, false, false, false, false, false, true, true, false, false, false, true, true, false, true, false, true, false, false, true, true, false, true, false, true, true, false, true, false, false, false, false, false, true, false, true, true, true, true, false, true, true, true, false, true, false, true, true, true, true, true, true, false, false, false, true, false, true, false, true, false, false, true, true, true, false, true, false, false, true, false, false, true, false, false, false, false, false, false, true, false, true, true, true, false, false, true, false, false, false, false, false, false, false, true, false, false, false, false, false, false, false, false, false, true, false, false, true, true, false, false, false, false, true, true, true, true, true, false, true, false, false, false, false, true, false, false, true, false, false, false, true, false, false, true, false, false, true, false, true, true, false, false, false, true, true, false, true, false, false, true, true, false, true, false, true, true, false, true, true, false, true, true, true, true, true, true, false, false, false, true, true, true, false, false, true, true, true, true, true, true, true, false, true, false, true, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, false, true, false, true, false, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, true, false, false, true, true, true, true, false, false, false, true, true, true, false, true, true, true, false, false, false, false, false, true, true, false, false, false, false, false, true, true, true, false, false, false, true, true, false, false, false, true, true, true, true, false, false, true, false, false, false, true, true, true, false, false, true, false, false, false, true, true, true, true, false, true, false, true, true, false, true, false, true, true, true, false, true, true, true, false, true, false, false, true, true, true, true, false, true, true, false, false, true, false, true, false, false, false, true, true, false, false, true, true, false, false, true, false, false, false, false, true, false, false, false, false, false, false, false, false, true, true, true, true, false, false, false, true, true, false, false, false, true, false, false, true, true, true, false, false, true, false, false, true, false, true, true, false, true, false, true, true, false, false, false, false, false, false, true, false, true, false, false, false, true, false, false, false, true, true, false, false, false, true, true, false, true, false, true, true, false, false, false, true, false, true, false, true, false, false, false, false, false, false, false, true, true, true, true, true]
 
 	bool[256] d = pedersen(e)
 
-	d == [false, false, false, false, false, true, true, false, true, true, false, true, true, true, true, true, true, false, true, false, true, true, false, false, true, false, true, false, false, false, false, false, true, true, false, true, true, false, false, false, false, false, true, false, true, true, false, false, false, false, false, false, false, true, true, true, true, false, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, true, true, true, true, false, false, false, false, true, true, true, true, false, true, true, false, false, true, false, true, true, true, true, false, true, true, false, false, true, true, false, false, true, false, true, false, false, true, true, false, false, false, true, true, false, false, false, false, false, false, false, false, false, true, false, true, false, false, true, true, true, true, true, false, true, true, true, true, false, false, false, true, false, false, true, true, true, true, true, false, false, false, true, false, true, true, false, true, false, false, false, true, false, false, true, false, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, false, false, true, false, false, true, true, false, false, false, true, false, true, false, false, true, true, true, true, true, false, false, false, true, false, true, false, false, true, true, false, true, false, true, true, true, false, false, false, false, false, false, true, false, true, false, true, false, false, false, true, false, true, false, false, false, false, false, true, false, true, false, false, false, false, false, false, false, true, false, true, true]
+	assert(d == [false, false, false, false, false, true, true, false, true, true, false, true, true, true, true, true, true, false, true, false, true, true, false, false, true, false, true, false, false, false, false, false, true, true, false, true, true, false, false, false, false, false, true, false, true, true, false, false, false, false, false, false, false, true, true, true, true, false, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, true, true, true, true, false, false, false, false, true, true, true, true, false, true, true, false, false, true, false, true, true, true, true, false, true, true, false, false, true, true, false, false, true, false, true, false, false, true, true, false, false, false, true, true, false, false, false, false, false, false, false, false, false, true, false, true, false, false, true, true, true, true, true, false, true, true, true, true, false, false, false, true, false, false, true, true, true, true, true, false, false, false, true, false, true, true, false, true, false, false, false, true, false, false, true, false, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, false, false, true, false, false, true, true, false, false, false, true, false, true, false, false, true, true, true, true, true, false, false, false, true, false, true, false, false, true, true, false, true, false, true, true, true, false, false, false, false, false, false, true, false, true, false, true, false, false, false, true, false, true, false, false, false, false, false, true, false, true, false, false, false, false, false, false, false, true, false, true, true])
 	
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.json b/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.json
index 41f66e25..9d170267 100644
--- a/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.json
+++ b/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.zok b/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.zok
index d81c875e..80413fa2 100644
--- a/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.zok
+++ b/zokrates_stdlib/tests/tests/hashes/pedersen/6bit.zok
@@ -8,12 +8,12 @@
 
 import "hashes/pedersen/6bit" as pedersen
 
-def main() -> (field):
+def main() -> ():
 	
 	bool[6] e = [true, true, false, false, false, false]
 	field[2] d = pedersen(e)
 
-	5483803361072598088157572477433311028290255512997784196805059543720485966024 == d[0]
-	8712718144085345152615259409576985937188455136179509057889474614313734076278 == d[1]
+	assert(5483803361072598088157572477433311028290255512997784196805059543720485966024 == d[0])
+	assert(8712718144085345152615259409576985937188455136179509057889474614313734076278 == d[1])
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.json b/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.json
index 2798cee6..503a8945 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.json
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.json
@@ -7,7 +7,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.zok b/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.zok
index 0a8066ee..fb6ed1ee 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.zok
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/1024bitPadded.zok
@@ -15,7 +15,7 @@
 // bin(int(digest, 16))
 // # '0b1110111110100100000111001010010010100101110001110110101101001001010111010101010111011111110110111111100100010111010100110010000001000000010010110011110010000000010010001011001110001110101100011000011100111010101001100110001100111010001101100011100010000011'
 import "hashes/sha256/1024bitPadded" as sha256
-def main() -> (field):
+def main() -> ():
 
 	bool[256] a = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
 	bool[256] b = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
@@ -24,6 +24,6 @@ def main() -> (field):
 
 	bool[256] digest = sha256(a, b, c, d)
 
-	digest == [true, true, true, false, true, true, true, true, true, false, true, false, false, true, false, false, false, false, false, true, true, true, false, false, true, false, true, false, false, true, false, false, true, false, true, false, false, true, false, true, true, true, false, false, false, true, true, true, false, true, true, false, true, false, true, true, false, true, false, false, true, false, false, true, false, true, false, true, true, true, false, true, false, true, false, true, false, true, false, true, true, true, false, true, true, true, true, true, true, true, false, true, true, false, true, true, true, true, true, true, true, false, false, true, false, false, false, true, false, true, true, true, false, true, false, true, false, false, true, true, false, false, true, false, false, false, false, false, false, true, false, false, false, false, false, false, false, true, false, false, true, false, true, true, false, false, true, true, true, true, false, false, true, false, false, false, false, false, false, false, false, true, false, false, true, false, false, false, true, false, true, true, false, false, true, true, true, false, false, false, true, true, true, false, true, false, true, true, false, false, false, true, true, false, false, false, false, true, true, true, false, false, true, true, true, false, true, false, true, false, true, false, false, true, true, false, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, false, false, false, true, true, false, true, true, false, false, false, true, true, true, false, false, false, true, false, false, false, false, false, true, true]
+	assert(digest == [true, true, true, false, true, true, true, true, true, false, true, false, false, true, false, false, false, false, false, true, true, true, false, false, true, false, true, false, false, true, false, false, true, false, true, false, false, true, false, true, true, true, false, false, false, true, true, true, false, true, true, false, true, false, true, true, false, true, false, false, true, false, false, true, false, true, false, true, true, true, false, true, false, true, false, true, false, true, false, true, true, true, false, true, true, true, true, true, true, true, false, true, true, false, true, true, true, true, true, true, true, false, false, true, false, false, false, true, false, true, true, true, false, true, false, true, false, false, true, true, false, false, true, false, false, false, false, false, false, true, false, false, false, false, false, false, false, true, false, false, true, false, true, true, false, false, true, true, true, true, false, false, true, false, false, false, false, false, false, false, false, true, false, false, true, false, false, false, true, false, true, true, false, false, true, true, true, false, false, false, true, true, true, false, true, false, true, true, false, false, false, true, true, false, false, false, false, true, true, true, false, false, true, true, true, false, true, false, true, false, true, false, false, true, true, false, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, false, false, false, true, true, false, true, true, false, false, false, true, true, true, false, false, false, true, false, false, false, false, false, true, true])
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/512bit.json b/zokrates_stdlib/tests/tests/hashes/sha256/512bit.json
index 3929ee11..64bd9658 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/512bit.json
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/512bit.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/512bit.zok b/zokrates_stdlib/tests/tests/hashes/sha256/512bit.zok
index f87a6d33..110a3108 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/512bit.zok
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/512bit.zok
@@ -1,11 +1,11 @@
 import "hashes/sha256/512bit" as sha256
-def main() -> (field):
+def main() -> ():
 
 bool[256] a = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
 bool[256] b = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true]
 
 bool[256] digest = sha256(a, b)
 
-digest == [false, false, false, true, true, true, true, true, false, false, true, true, true, false, true, true, true, false, false, false, true, false, true, true, true, false, false, true, true, false, false, false, true, true, false, false, false, false, true, false, false, false, false, true, true, true, true, false, true, false, true, true, true, false, false, false, true, false, false, true, false, true, false, false, false, false, true, true, true, true, false, false, true, false, false, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, false, false, true, false, true, true, false, false, false, false, false, true, false, true, false, false, false, false, false, true, false, true, false, false, true, false, true, true, false, true, true, false, false, false, false, true, false, false, false, false, false, true, false, true, false, true, false, true, false, true, true, false, false, false, true, false, false, true, true, false, false, false, false, true, false, true, false, false, true, true, true, false, false, true, true, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, true, true, false, true, false, true, true, true, true, false, true, true, true, true, false, false, false, true, false, false, true, true, true, false, true, false, false, false, false, false, false, true, true, true, true, false, true, true, true, true, true, false, true, false, true, false, true, true, false, false, true, true, false, false, false, false, true, true, true, true, false, true, false, false, true, false, true, true, false, true]
+assert(digest == [false, false, false, true, true, true, true, true, false, false, true, true, true, false, true, true, true, false, false, false, true, false, true, true, true, false, false, true, true, false, false, false, true, true, false, false, false, false, true, false, false, false, false, true, true, true, true, false, true, false, true, true, true, false, false, false, true, false, false, true, false, true, false, false, false, false, true, true, true, true, false, false, true, false, false, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, false, false, true, false, true, true, false, false, false, false, false, true, false, true, false, false, false, false, false, true, false, true, false, false, true, false, true, true, false, true, true, false, false, false, false, true, false, false, false, false, false, true, false, true, false, true, false, true, false, true, true, false, false, false, true, false, false, true, true, false, false, false, false, true, false, true, false, false, true, true, true, false, false, true, true, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, true, true, false, true, false, true, true, true, true, false, true, true, true, true, false, false, false, true, false, false, true, true, true, false, true, false, false, false, false, false, false, true, true, true, true, false, true, true, true, true, true, false, true, false, true, false, true, true, false, false, true, true, false, false, false, false, true, true, true, true, false, true, false, false, true, false, true, true, false, true])
 
-return 1
\ No newline at end of file
+return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked.zok b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked.zok
index 7387fe09..80ef3436 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked.zok
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked.zok
@@ -16,7 +16,7 @@
 // # 65303172752238645975888084098459749904
 
 import "hashes/sha256/512bitPacked" as sha256packed
-def main() -> (field):
+def main() -> ():
 
 	field a = 0
 	field b = 0
@@ -25,7 +25,7 @@ def main() -> (field):
 
 	field[2] h = sha256packed([a, b, c, d])
 	
-	h[0] == 263561599766550617289250058199814760685
-	h[1] == 65303172752238645975888084098459749904
+	assert(h[0] == 263561599766550617289250058199814760685)
+	assert(h[1] == 65303172752238645975888084098459749904)
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked2.json b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked2.json
index dfe7af8c..c4d22fc2 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked2.json
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPacked2.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.json b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.json
index d34c5ebb..8345033f 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.json
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.zok b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.zok
index 16872273..46ca0f87 100644
--- a/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.zok
+++ b/zokrates_stdlib/tests/tests/hashes/sha256/512bitPadded.zok
@@ -13,14 +13,14 @@
 // bin(int(digest, 16))
 // # '0b1100011001001000000111100010001011000101111111110100000101100100101011110110100000001011100011001111101010100101111010001110110100110001001000001110111011111111100010011100010011110011000001111100010010100110111110101010101011100000010110011100111000010000'
 import "hashes/sha256/512bitPadded" as sha256
-def main() -> (field):
+def main() -> ():
 
-bool[256] a = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
-bool[256] b = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true]
+	bool[256] a = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
+	bool[256] b = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true]
 
 	bool[256] digest = sha256(a, b)
 
-	digest == [true, true, false, false, false, true, true, false, false, true, false, false, true, false, false, false, false, false, false, true, true, true, true, false, false, false, true, false, false, false, true, false, true, true, false, false, false, true, false, true, true, true, true, true, true, true, true, true, false, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, true, false, true, false, true, true, true, true, false, true, true, false, true, false, false, false, false, false, false, false, true, false, true, true, true, false, false, false, true, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, true, true, true, true, false, true, false, false, false, true, true, true, false, true, true, false, true, false, false, true, true, false, false, false, true, false, false, true, false, false, false, false, false, true, true, true, false, true, true, true, false, true, true, true, true, true, true, true, true, true, false, false, false, true, false, false, true, true, true, false, false, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, false, false, true, true, true, true, true, false, false, false, true, false, false, true, false, true, false, false, true, true, false, true, true, true, true, true, false, true, false, true, false, true, false, true, false, true, false, true, true, true, false, false, false, false, false, false, true, false, true, true, false, false, true, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, false]
+	assert(digest == [true, true, false, false, false, true, true, false, false, true, false, false, true, false, false, false, false, false, false, true, true, true, true, false, false, false, true, false, false, false, true, false, true, true, false, false, false, true, false, true, true, true, true, true, true, true, true, true, false, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, true, false, true, false, true, true, true, true, false, true, true, false, true, false, false, false, false, false, false, false, true, false, true, true, true, false, false, false, true, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, true, true, true, true, false, true, false, false, false, true, true, true, false, true, true, false, true, false, false, true, true, false, false, false, true, false, false, true, false, false, false, false, false, true, true, true, false, true, true, true, false, true, true, true, true, true, true, true, true, true, false, false, false, true, false, false, true, true, true, false, false, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, false, false, true, true, true, true, true, false, false, false, true, false, false, true, false, true, false, false, true, true, false, true, true, true, true, true, false, true, false, true, false, true, false, true, false, true, false, true, true, true, false, false, false, false, false, false, true, false, true, true, false, false, true, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, false])
 
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.json b/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.json
index 3bb02726..a9475c28 100644
--- a/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.json
+++ b/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.zok b/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.zok
index 7ba74bc0..ba6f8bec 100644
--- a/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.zok
+++ b/zokrates_stdlib/tests/tests/hashes/utils/256bitsDirectionHelper.zok
@@ -14,27 +14,27 @@
 
 import "hashes/utils/256bitsDirectionHelper" as direction
 
-def left() -> (field):
+def left() -> (bool):
 
 	bool[256] a = [false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false]
 	bool[256] b = [false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true]
 
 	bool[512] out = direction(false, a, b)
-	out == [false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true]
-	return 1
+	assert(out == [false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true])
+	return true
 
-def right() -> (field):
+def right() -> (bool):
 
 	bool[256] a = [false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false]
 	bool[256] b = [false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true]
 
 	bool[512] out = direction(true, a, b)
-	out == [false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true, false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false]
-	return 1
+	assert(out == [false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true, false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false])
+	return true
 
-def main() -> (field):
+def main() -> ():
 	
-	left() == 1
-	right() == 1
+	assert(left())
+	assert(right())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/signatures/verifyEddsa.json b/zokrates_stdlib/tests/tests/signatures/verifyEddsa.json
index 3bb73523..f6b36bc0 100644
--- a/zokrates_stdlib/tests/tests/signatures/verifyEddsa.json
+++ b/zokrates_stdlib/tests/tests/signatures/verifyEddsa.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/signatures/verifyEddsa.zok b/zokrates_stdlib/tests/tests/signatures/verifyEddsa.zok
index 09dfe7a5..7b3bd2cd 100644
--- a/zokrates_stdlib/tests/tests/signatures/verifyEddsa.zok
+++ b/zokrates_stdlib/tests/tests/signatures/verifyEddsa.zok
@@ -4,7 +4,7 @@ from "ecc/babyjubjubParams" import BabyJubJubParams
 
 // Code to create test case:
 // https://github.com/Zokrates/pycrypto
-def main() -> (field):
+def main() -> ():
 
 	BabyJubJubParams context = context()
 
@@ -18,6 +18,6 @@ def main() -> (field):
     bool[256] M1 = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true]
 
     bool isVerified = verifyEddsa(R, S, A, M0, M1, context)
-    isVerified == true
+    assert(isVerified)
 
-    return 1
\ No newline at end of file
+    return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.json b/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.json
index 3a9fb8dd..420e1c27 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.json
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.zok b/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.zok
index 08eae996..35c0015c 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.zok
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/256bit.zok
@@ -1,6 +1,6 @@
 import "utils/multiplexer/256bit" as multiplex
 
-def left() -> (field):
+def left() -> (bool):
 	bool bit = false  //left
 
 	bool[256] a = [false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false]
@@ -8,11 +8,11 @@ def left() -> (field):
 	bool[256] b = [false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true]
 
 	bool[256] output = [false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false]
-	output == multiplex(bit, a, b)
+	assert(output == multiplex(bit, a, b))
 	
-	return 1
+	return true
 	
-def right() -> (field):
+def right() -> (bool):
 	bool bit = true  //right
 
 	bool[256] a = [false, false, false, true, true, false, true, true, false, false, false, true, true, false, false, true, true, true, false, true, true, true, true, false, true, false, true, false, true, false, false, false, true, false, true, true, true, false, true, false, false, true, false, false, true, true, true, false, false, false, true, true, true, true, false, false, false, false, false, true, false, true, true, false, false, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, true, true, false, false, true, true, true, true, false, true, false, false, true, false, false, false, false, true, false, false, true, true, false, false, true, true, false, false, true, true, true, true, true, true, true, true, true, false, true, false, false, true, true, true, true, false, false, true, true, false, false, false, true, false, true, false, false, false, false, true, false, true, false, false, false, false, true, true, false, false, false, true, false, false, true, true, true, true, true, false, true, false, true, false, true, false, false, true, false, false, true, false, true, true, true, false, true, true, true, true, true, true, false, false, false, true, false, true, true, true, true, true, false, false, false, true, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, true, true, false, true, true, true, false, true, true, true, false, false, false, true, true, false, false, true, true, false, false, true, false, true, false, true, true, false, false, true, false, true, false, true, false, false, false, true, true, true, false, false, false]
@@ -20,13 +20,13 @@ def right() -> (field):
 	bool[256] b = [false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true]
 	
 	bool[256] output = [false, false, false, false, false, false, true, true, true, true, true, true, false, false, true, true, true, true, true, true, false, true, true, false, false, false, true, false, true, false, false, false, true, true, true, false, false, false, false, false, false, true, true, false, false, true, true, true, false, true, false, true, false, false, true, false, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, false, true, true, false, true, true, false, true, true, true, true, false, true, true, true, false, false, false, true, false, true, false, false, true, false, true, false, false, true, false, true, true, false, true, true, true, false, true, false, true, false, false, false, false, true, true, false, true, true, false, false, true, true, false, true, false, false, true, false, true, true, false, true, true, false, true, true, true, true, false, false, true, false, true, false, true, true, true, false, false, false, false, true, true, true, false, true, false, false, true, true, false, true, true, true, true, true, true, false, false, false, false, false, false, false, true, true, false, true, false, false, true, false, true, true, false, false, true, true, true, false, false, false, false, true, false, false, false, true, true, true, true, false, false, false, false, true, true, false, true, true, false, true, true, true, true, false, false, false, true, true, true, true, true, false, true, true, false, true, true, false, true, true, true, false, false, false, true, false, true, true, false, true, false, true, false, true, false, true, false, true, true, true]
-	output == multiplex(bit, a, b)
+	assert(output == multiplex(bit, a, b))
 	
-	return 1
+	return true
 	
-def main() -> (field):
+def main() -> ():
 
-	1 == left()
-	1 == right()
+	assert(left())
+	assert(right())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.json b/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.json
index e228f142..750472d6 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.json
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.zok b/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.zok
index e7a2748f..2e7b1907 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.zok
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/2bit.zok
@@ -1,28 +1,28 @@
 import "utils/multiplexer/2bit" as multiplex
 
-def left() -> (field):
+def left() -> (bool):
 	bool bit = false  //left
 	bool[2] a  = [false, true]
 	bool[2] b = [true, false]
 	
 	bool[2] output = [false, true]
-	output == multiplex(bit, a, b)
+	assert(output == multiplex(bit, a, b))
 	
-	return 1
+	return true
 	
-def right() -> (field):
+def right() -> (bool):
 	bool bit = true  //right
 	bool[2] a  = [false, true]
 	bool[2] b = [true, false]
 	
 	bool[2] output = [true, false]
-	output == multiplex(bit, a, b)
+	assert(output == multiplex(bit, a, b))
 	
-	return 1
+	return true
 	
-def main() -> (field):
+def main() -> ():
 
-	1 == left()
-	1 == right()
+	assert(left())
+	assert(right())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.json b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.json
index 18cb968b..3e2cbc25 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.json
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.zok b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.zok
index b98b0c52..76cd4ef3 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.zok
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup1bit.zok
@@ -1,24 +1,24 @@
 import "utils/multiplexer/lookup1bit" as lookup
 
-def left() -> (field):
+def left() -> (bool):
 	bool sel = false  //left
 	field[2] t  = [0, 1]
 	
-	0 == lookup(sel, t)
+	assert(0 == lookup(sel, t))
 	
-	return 1
+	return true
 	
-def right() -> (field):
+def right() -> (bool):
 	bool sel = true  //right
 	field[2] t = [0, 1]
 	
-	1 == lookup(sel, t)
+	assert(1 == lookup(sel, t))
 	
-	return 1
+	return true
 	
-def main() -> (field):
+def main() -> ():
 
-	1 == left()
-	1 == right()
+	assert(left())
+	assert(right())
 
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.json b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.json
index c4fd2436..2d2f4fab 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.json
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.zok b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.zok
index 1022578c..58185aac 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.zok
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup2bit.zok
@@ -1,42 +1,42 @@
 import "utils/multiplexer/lookup2bit" as lookup
 
-def first() -> (field):
+def first() -> (bool):
 	bool[2] sel = [false, false]
 	field[4] t  = [0, 1, 2, 3]
 	
-	0 == lookup(sel, t)
+	assert(0 == lookup(sel, t))
 	
-	return 1
+	return true
 	
-def second() -> (field):
+def second() -> (bool):
 	bool[2] sel = [true, false]
 	field[4] t  = [0, 1, 2, 3]
 	
-	1 == lookup(sel, t)
+	assert(1 == lookup(sel, t))
 	
-	return 1
+	return true
 	
-def third() -> (field):
+def third() -> (bool):
 	bool[2] sel = [false, true]
 	field[4] t  = [0, 1, 2 , 3]
 	
-	2 == lookup(sel, t)
+	assert(2 == lookup(sel, t))
 	
-	return 1
+	return true
 
-def fourth() -> (field):
+def fourth() -> (bool):
 	bool[2] sel = [true, true]
 	field[4] t  = [0, 1, 2 , 3]
 	
-	3 == lookup(sel, t)
+	assert(3 == lookup(sel, t))
 	
-	return 1
+	return true
 	
-def main() -> (field):
+def main() -> ():
 
-	1 == first()
-	1 == second()
-	1 == third()
-	1 == fourth()
+	assert(first())
+	assert(second())
+	assert(third())
+	assert(fourth())
 	
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.json b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.json
index f8817f50..5c77d558 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.json
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.zok b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.zok
index 14c58019..f42c52bd 100644
--- a/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.zok
+++ b/zokrates_stdlib/tests/tests/utils/multiplexer/lookup3bitSigned.zok
@@ -1,81 +1,81 @@
 import "utils/multiplexer/lookup3bitSigned" as lookup
 
-def first() -> (field):
+def first() -> (bool):
 	bool[3] sel = [false,false,false]
 	field[4] t  = [0, 1, 2 , 3]
 	
-	0 == lookup(sel, t)
+	assert(0 == lookup(sel, t))
 	
-	return 1
+	return true
 
-def firstNeg() -> (field):
+def firstNeg() -> (bool):
 	bool[3] sel = [false,false,true]
 	field[4] t  = [0, 1, 2 , 3]
 	
-	0 == lookup(sel, t)
+	assert(0 == lookup(sel, t))
 	
-	return 1
+	return true
 
-def second() -> (field):
+def second() -> (bool):
 	bool[3] sel = [true,false,false]
 	field[4] t  = [0, 1, 2 , 3]
 	
-	1 == lookup(sel, t)
+	assert(1 == lookup(sel, t))
 	
-	return 1
+	return true
 
-def secondNeg() -> (field):
+def secondNeg() -> (bool):
 	bool[3] sel = [true,false,true]
 	field[4] t  = [0, 1, 2 , 3]
 	
 	field out = 0 - 1
-	out == lookup(sel, t)
+	assert(out == lookup(sel, t))
 	
-	return 1
+	return true
 
-def thrid() -> (field):
+def thrid() -> (bool):
 	bool[3] sel = [false,true,false]
 	field[4] t  = [0, 1, 2 , 3]
 	
-	2 == lookup(sel, t)
+	assert(2 == lookup(sel, t))
 	
-	return 1
+	return true
 
-def thridNeg() -> (field):
+def thridNeg() -> (bool):
 	bool[3] sel = [false,true,true]
 	field[4] t  = [0, 1, 2 , 3]
 	
 	field out = 0 - 2
-	out == lookup(sel, t)
+	assert(out == lookup(sel, t))
 	
-	return 1
+	return true
 
-def fourth() -> (field):
+def fourth() -> (bool):
 	bool[3] sel = [true,true,false]
 	field[4] t  = [0, 1, 2 , 3]
 	
-	3 == lookup(sel, t)
+	assert(3 == lookup(sel, t))
 	
-	return 1
+	return true
 
-def fourthNeg() -> (field):
+def fourthNeg() -> (bool):
 	bool[3] sel = [true,true,true]
 	field[4] t  = [0, 1, 2 , 3]
 	
 	field out = 0 - 3
-	out == lookup(sel, t)
+	assert(out == lookup(sel, t))
 	
-	return 1
+	return true
 	
-def main() -> (field):
+def main() -> ():
 
-	1 == first()
-	1 == firstNeg()
-	1 == second()
-	1 == secondNeg()
-	1 == thrid()
-	1 == thridNeg()
-	1 == fourth()
-	1 == fourthNeg()
+	assert(first())
+	assert(firstNeg())
+	assert(second())
+	assert(secondNeg())
+	assert(thrid())
+	assert(thridNeg())
+	assert(fourth())
+	assert(fourthNeg())
 	
-	return 1
\ No newline at end of file
+	return
\ No newline at end of file
diff --git a/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.json b/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.json
index fe66a5c8..5ccd6551 100644
--- a/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.json
+++ b/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.zok b/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.zok
index acdf18e1..09f46fc0 100644
--- a/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.zok
+++ b/zokrates_stdlib/tests/tests/utils/pack/nonStrictUnpack256.zok
@@ -1,41 +1,41 @@
 import "utils/pack/nonStrictUnpack256" as unpack256
 
-def testFive() -> (field):
+def testFive() -> (bool):
 
 	bool[256] b = unpack256(5)
 
-	b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true ]
+	assert(b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true ])
 
-	return 1
+	return true
 
-def testZero() -> (field):
+def testZero() -> (bool):
 
 	bool[256] b = unpack256(0)
 
-	b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false ]
+	assert(b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false ])
 
-	return 1
+	return true
 
-def testLarge() -> (field):
+def testLarge() -> (bool):
 
 	bool[256] b = unpack256(14474011154664524427946373126085988481658748083205070504932198000989141204991)
 
-	b == [false, false, false, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true ]
+	assert(b == [false, false, false, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true ])
 
-	return 1
+	return true
 
-def testMax() -> (field):
+def testMax() -> (bool):
 
 	bool[256] b = unpack256(21888242871839275222246405745257275088548364400416034343698204186575808495616)
 
-	b == [false, false, true, true, false, false, false, false, false, true, true, false, false, true, false, false, false, true, false, false, true, true, true, false, false, true, true, true, false, false, true, false, true, true, true, false, false, false, false, true, false, false, true, true, false, false, false, true, true, false, true, false, false, false, false, false, false, false, true, false, true, false, false, true, true, false, true, true, true, false, false, false, false, true, false, true, false, false, false, false, false, true, false, false, false, true, false, true, true, false, true, true, false, true, true, false, true, false, false, false, false, false, false, true, true, false, false, false, false, false, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, false, true, false, false, true, false, true, false, false, false, false, false, true, true, false, false, true, true, true, true, true, false, true, false, false, false, false, true, false, false, true, false, false, false, false, true, true, true, true, false, false, true, true, false, true, true, true, false, false, true, false, true, true, true, false, false, false, false, true, false, false, true, false, false, false, true, false, true, false, false, false, false, true, true, true, true, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, false, true, false, false, true, true, true, true, true, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false ]
+	assert(b == [false, false, true, true, false, false, false, false, false, true, true, false, false, true, false, false, false, true, false, false, true, true, true, false, false, true, true, true, false, false, true, false, true, true, true, false, false, false, false, true, false, false, true, true, false, false, false, true, true, false, true, false, false, false, false, false, false, false, true, false, true, false, false, true, true, false, true, true, true, false, false, false, false, true, false, true, false, false, false, false, false, true, false, false, false, true, false, true, true, false, true, true, false, true, true, false, true, false, false, false, false, false, false, true, true, false, false, false, false, false, false, true, false, true, false, true, true, false, false, false, false, true, false, true, true, true, false, true, false, false, true, false, true, false, false, false, false, false, true, true, false, false, true, true, true, true, true, false, true, false, false, false, false, true, false, false, true, false, false, false, false, true, true, true, true, false, false, true, true, false, true, true, true, false, false, true, false, true, true, true, false, false, false, false, true, false, false, true, false, false, false, true, false, true, false, false, false, false, true, true, true, true, true, false, false, false, false, true, true, true, true, true, false, true, false, true, true, false, false, true, false, false, true, true, true, true, true, true, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false ])
 
-	return 1
+	return true
 
- def main() -> (field):
+ def main() -> ():
 
-	1 == testFive()
-	1 == testMax()
-	1 == testZero()
-	1 == testLarge()
-	return 1
+	assert(testFive())
+	assert(testMax())
+	assert(testZero())
+	assert(testLarge())
+	return
diff --git a/zokrates_stdlib/tests/tests/utils/pack/pack128.json b/zokrates_stdlib/tests/tests/utils/pack/pack128.json
index f581763f..41d03731 100644
--- a/zokrates_stdlib/tests/tests/utils/pack/pack128.json
+++ b/zokrates_stdlib/tests/tests/utils/pack/pack128.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/pack/pack128.zok b/zokrates_stdlib/tests/tests/utils/pack/pack128.zok
index 11ff1ff4..9ae34334 100644
--- a/zokrates_stdlib/tests/tests/utils/pack/pack128.zok
+++ b/zokrates_stdlib/tests/tests/utils/pack/pack128.zok
@@ -1,36 +1,36 @@
 import "utils/pack/pack128" as pack128
 
-def testFive() -> (field):
+def testFive() -> (bool):
 
 	bool[128] b = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true]
 	field n = pack128(b)
 
-	5 == n
+	assert(5 == n)
 
-	return 1
+	return true
 
-def testZero() -> (field):
+def testZero() -> (bool):
 
 	bool[128] b = [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
 	field n = pack128(b)
 
-	0 == n
+	assert(0 == n)
 
-	return 1
+	return true
 
-def testMax() -> (field):
+def testMax() -> (bool):
 
 	bool[128] b = [true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true]
 	field n = pack128(b)
 
-	340282366920938463463374607431768211455 == n
+	assert(340282366920938463463374607431768211455 == n)
 
-	return 1
+	return true
 
- def main() -> (field):
+ def main() -> ():
 
-	1 == testFive()
-	1 == testMax()
-	1 == testZero()
+	assert(testFive())
+	assert(testMax())
+	assert(testZero())
 
-	return 1
+	return
diff --git a/zokrates_stdlib/tests/tests/utils/pack/unpack128.json b/zokrates_stdlib/tests/tests/utils/pack/unpack128.json
index b5f7768f..3e9e5085 100644
--- a/zokrates_stdlib/tests/tests/utils/pack/unpack128.json
+++ b/zokrates_stdlib/tests/tests/utils/pack/unpack128.json
@@ -8,7 +8,7 @@
 			},
 			"output": {
 				"Ok": {
-					"values": ["1"]
+					"values": []
 				}
 			}
 		}
diff --git a/zokrates_stdlib/tests/tests/utils/pack/unpack128.zok b/zokrates_stdlib/tests/tests/utils/pack/unpack128.zok
index 2b81cd34..008f75b4 100644
--- a/zokrates_stdlib/tests/tests/utils/pack/unpack128.zok
+++ b/zokrates_stdlib/tests/tests/utils/pack/unpack128.zok
@@ -1,33 +1,33 @@
 import "utils/pack/unpack128" as unpack128
 
-def testFive() -> (field):
+def testFive() -> (bool):
 
 	bool[128] b = unpack128(5)
 
-	b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true]
+	assert(b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, true, false, true])
 
-	return 1
+	return true
 
-def testZero() -> (field):
+def testZero() -> (bool):
 
 	bool[128] b = unpack128(0)
 
-	b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false]
+	assert(b == [false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false, false])
 
-	return 1
+	return true
 
-def testMax() -> (field):
+def testMax() -> (bool):
 
 	bool[128] b = unpack128(340282366920938463463374607431768211455)
 
-	b == [true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true]
+	assert(b == [true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true, true])
 
-	return 1
+	return true
 
- def main() -> (field):
+ def main() -> ():
 
-	1 == testFive()
-	1 == testMax()
-	1 == testZero()
+	assert(testFive())
+	assert(testMax())
+	assert(testZero())
 
-	return 1
+	return