%---------------------------------------------------------------------------%
% vim: ts=4 sw=4 et ft=mercury
%---------------------------------------------------------------------------%

:- module browser_mode.
:- interface.
:- import_module io.

:- pred main(io__state::di, io__state::uo) is det.

:- implementation.

:- import_module char.
:- import_module int.
:- import_module std_util.

main -->
    ( { p('a', X), test(X) } ->
        io__write_string("yes\n")
    ;
        io__write_string("no\n")
    ).

:- pred test(int).
:- mode test(in) is semidet.

test(_) :-
    semidet_fail.

:- pred p(char, int).
:- mode p(in, out) is nondet.

p(A, D) :-
    q(A, B),
    (
        r(B, C)
    ->
        (
            s(C, D)
        ;
            D = 31
        )
    ;
        not(
            q(B, _)
        ),
        D = 32
    ).

:- pred q(char, char).
:- mode q(in, out) is nondet.

q('a', 'a').
q('a', 'b').
q('c', 'c').

:- pred r(char, int).
:- mode r(in, out) is semidet.

r('a', 10).

:- pred s(int, int).
:- mode s(in, out) is det.

s(N, 3 * N).