concept Foo<Z> {
  type bar;
  fun fooey(Z x) -> bar@;
};

fun yikes<S, T> where { Foo<S> }
(Foo<S>.bar u, S s, T t) -> S { return s; }


fun zow<T> where { Foo<T> }
(T t) -> T
{
  return yikes(fooey(t), t, t);
}

struct foo {
  int x;
};

model Foo<foo> {
  type bar = int;
  fun fooey(foo f) -> int@ {
    return f.x;
  }
};

fun main() -> int@ {
  let f = @foo{ x = 3 };
  return 3 - zow(f).x;
}