type FieldArray<N> = field[N]

struct Foo<A, B> {
    FieldArray<A> a
    FieldArray<B> b
}

type Bar = Foo<2, 2>
type Buzz<A> = Foo<A, A>

def main(Bar a) -> Buzz<2>:
    Bar bar = Bar { a: [1, 2], b: [1, 2] }
    Buzz<2> buzz = Buzz { a: [1, 2], b: [1, 2] }
    assert(bar == buzz)
    return buzz