polymorphic_bounded_overload.chr

:- module(polymorphic_bounded_overload, [result/1]).
:- use_module(library(prelude)).

:- chr_constraint result(any).

% A polymorphic function whose body calls an overloaded operator at
% the declaration's own type variable. The `requiring '>'(T, T) -> bool`
% clause contributes an ambient signature for `>` at the rigid T, so
% the body call resolves through the ambient and the equation type-checks.
% At the use site `foo(3, 4)`, σ = (T := int) and the bound discharges
% against the prelude's declared `'>'(int, int) -> bool`.
:- function foo(T, T) -> bool requiring '>'(T, T) -> bool.

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

result(R) <=> R is foo(3, 4).