Files
mercury/tests/hard_coded/functor_ho_inst.m
2020-10-05 17:53:05 +11:00

48 lines
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Mathematica

%---------------------------------------------------------------------------%
% vim: ts=4 sw=4 et ft=mercury
%---------------------------------------------------------------------------%
%
% Use a functor with a higher-order argument with an inst.
%
:- module functor_ho_inst.
:- interface.
:- import_module io.
:- pred main(io::di, io::uo) is det.
:- implementation.
%---------------------------------------------------------------------------%
:- import_module list.
main(!IO) :-
Jobs = [job(j1), job(j2)],
list.foldl(run, Jobs, !IO).
%---------------------------------------------------------------------------%
:- type job
---> job(pred(job_result::out, io::di, io::uo) is det).
:- type job_result
---> job_result_ok
; job_result_failed.
:- pred run(job::in, io::di, io::uo) is det.
run(Job, !IO) :-
Job = job(Pred),
Pred(Result, !IO),
io.write_line(Result, !IO).
:- pred j1(job_result::out, io::di, io::uo) is det.
j1(job_result_ok, !IO).
:- pred j2(job_result::out, io::di, io::uo) is det.
j2(job_result_failed, !IO).