[m-users.] Threads and cc_multi-ness

[Volker Wysk]

Hi!

I've tried a trivial program using threads:


:- pred main(io::di, io::uo) is cc_multi.

...

main(!IO) :-
    spawn(thread(88), !IO),
    io.write_string("99\n", !IO).

:- pred thread(int, io, io).
:- mode thread(in, di, uo) is cc_multi.

thread(I, !IO) :-
    io.format("I=%i\n", [i(I)], !IO).


Both main/2 and my thread/3 need to be cc_multi. What surprises me, is that
I get a compiler warning:


threads.m:021: In `thread'(in, di, uo):
threads.m:021:   warning: determinism declaration could be tighter.
threads.m:021:   Declared `cc_multi', inferred `det'.


... But the samples in samples/concurrency/dining_philosophers, which do it
like my trivial program, get compiled without such a warning message.

I think the warning isn't correct - the determinism declaration could NOT be
tighter. The mode of the spawn/3 predicate forbids making it "det".

So, what about this warning message? Just ignore?

Cheers,
Volker
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