constraint_has_equations.chr

:- module(constraint_has_equations, [result/1]).
:- chr_constraint result(any), foo(any).

% Forbidden: 'foo/1' is declared as a CHR constraint but has a function
% equation. Constraint names cannot define equations; either remove the
% equation or redeclare 'foo' as ':- function'.
foo(X) -> X.

result(R) <=> R is foo(1).