%---------------------------------------------------------------------------%
% vim: ts=4 sw=4 et ft=mercury
%---------------------------------------------------------------------------%
%
:- module trust_1.

:- interface.

:- import_module string.

:- type w
    --->    w(string)
    where comparison is w_cmp.

:- pred w_cmp(builtin.comparison_result::uo, w::in, w::in) is det.

:- implementation.

w_cmp(R, W1, W2) :-
    promise_equivalent_solutions [R1] (
        W1 = w(S1),
        W2 = w(S2),
        compare(R1, to_upper(S1) : string, to_upper(S2))
    ),
    R = unsafe_promise_unique(R1).