method_impl.m:026: In clause for type class method implementation:
method_impl.m:026:   in argument 2 of predicate `method_impl.foo_m1'/2:
method_impl.m:026:   type error: variable `HeadVar__2' has type
method_impl.m:026:     int;
method_impl.m:026:   expected type was
method_impl.m:026:     string.
method_impl.m:026:   The partial type assignment was:
method_impl.m:026:     HeadVar__1_1: method_impl.foo
method_impl.m:026:     HeadVar__2_2: int
method_impl.m:029: In clause for type class method implementation:
method_impl.m:029:   error: undefined predicate `bar_m1'/2.