use function syntax for log, reserve log, add test

zokrates_ast/src/typed/mod.rs

@@ -715,7 +715,7 @@ impl<'ast, T: fmt::Display> fmt::Display for TypedStatement<'ast, T> {
             }
             TypedStatement::Log(ref l, ref expressions) => write!(
                 f,
-                "log!({}, {})",
+                "log({}, {})",
                 l,
                 expressions
                     .iter()

zokrates_ast/src/untyped/mod.rs

@@ -431,7 +431,7 @@ impl<'ast> fmt::Display for Statement<'ast> {
             }
             Statement::Log(ref l, ref expressions) => write!(
                 f,
-                "log!({}, {})",
+                "log({}, {})",
                 l,
                 expressions
                     .iter()

zokrates_ast/src/zir/mod.rs

@@ -181,7 +181,7 @@ impl<'ast, T: fmt::Display> ZirStatement<'ast, T> {
             }
             ZirStatement::Log(ref l, ref expressions) => write!(
                 f,
-                "log!(\"{}\"), {})",
+                "log(\"{}\"), {})",
                 l,
                 expressions
                     .iter()

zokrates_cli/examples/book/logging.zok

@@ -4,6 +4,6 @@ struct Foo {
 }
 
 def main(Foo x, field y) {
-    log!("x is {}, y is {}", x, y);
+    log("x is {}, y is {}", x, y);
     return;
 }

zokrates_cli/examples/compile_errors/reserved_log.zok

@@ -0,0 +1,6 @@
+// "log" is reserved
+def log():
+    return
+
+def main()
+    return 

zokrates_parser/src/zokrates.pest

@@ -59,7 +59,7 @@ statement = { (iteration_statement // does not require semicolon
                 | assertion_statement
                 ) ~ semicolon)) ~ NEWLINE* }
 
-log_statement = { "log!(\"" ~ format_string ~ "\"" ~ "," ~ expression_list ~ ")"}
+log_statement = { "log" ~ "(" ~ "\"" ~ format_string ~ "\"" ~ "," ~ expression_list ~ ")"}
 format_string = { (!"\"" ~ ANY)* }
 block_statement = _{ "{" ~ NEWLINE* ~ statement* ~ NEWLINE* ~ "}" }
 iteration_statement = { "for" ~ typed_identifier ~ "in" ~ expression ~ ".." ~ expression ~ block_statement }
@@ -181,6 +181,6 @@ COMMENT = _{ ("/*" ~ (!"*/" ~ ANY)* ~ "*/") | ("//" ~ (!NEWLINE ~ ANY)*) }
 // 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"|"const"|"def"|"else"|"false"|"field"|"for"|"if"|"then"|"fi"|"import"|"from"|
+    "log"|"assert"|"as"|"bool"|"const"|"def"|"else"|"false"|"field"|"for"|"if"|"then"|"fi"|"import"|"from"|
     "in"|"mut"|"private"|"public"|"return"|"struct"|"true"|"u8"|"u16"|"u32"|"u64"
 }