polymorphic_unbounded_overload.chr

:- module(polymorphic_unbounded_overload, [foo/2]).
:- use_module(library(prelude)).

% A polymorphic function whose body calls an overloaded operator at
% the declaration's own type variable, with no `requiring` clause to
% contribute an ambient signature. Under rigid type variables this
% must fail: the prelude declares `>` only at (int, int) -> bool and
% (float, float) -> bool, neither of which is consistent with the
% rigid T. Adding `requiring '>'(T, T) -> bool` to the signature
% makes this program type-check.
:- function foo(T, T) -> bool.

foo(X, Y) -> X > Y.