class_with_requiring.chr

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

:- chr_constraint result(int).

:- class (gt(int, int) -> bool).
gt(X, Y) -> X > Y.

% Forbidden: requiring is reserved for :- function / :- open_function.
% Producing a :- class with a requiring clause is rejected as
% RequiringOnClass (YCHR-15005).
:- class pick(T, T) -> T requiring gt(T, T) -> bool.

pick(X, _) -> X.

result(R) <=> R is pick(1, 2).