How can the module for a term/goal/predicate be identified? In looking at the source code for SWI-Prolog I often see M:Goal so tried :- module(some_code,[]). create(Stack) :- Stack = stack([]). :- begin_tests(some_tests). test(1) :- create(Stack), assertion( Stack == stack([]) ). t…

Predicates have modules. Terms are just terms. [image] EricGT: test(2,[fail]) :- create(Stack), Stack = Module:Structure, assertion( Module == some_code ), assertion( Structure == stack() ). Here, stack is expected to be module qualified. It’s not, it’s just stack/1, so it fails.

@EricGT Have a look at the documentation about defining a meta-predicate . A meta_predicate/1 directive will cause the system to pass Module:Argument instead of just Argument, where Module is the module calling context the call is made in. Note that there is reduction, so that m1:(m2:foo) becomes m2:…

[image] michaelby: A meta_predicate/1 directive will cause the system to pass Module:Argument instead of just Argument , where Module is the module calling context the call is made in. Thanks Several days ago I posted a question about meta_predicate/1 and received no answers after a day so I…

[image] EricGT: Several days ago I posted a question about meta_predicate/1 and received no answers after a day so I deleted it and dug in deeper and found what I posted above. Your one line is now adding much more clarity; enough so that I plan to revisit the problem again using this insight. …

I have read your paper, @pmoura , the other day when I was thinking it might be possible to (from the Web Prolog user’s point of view) get rid of modules and the complications with meta_predicate/1 altogether. (It doesn’t seem likely though, as long as the workspace of an actor is provided by a modu…

[image] torbjorn.lager: Since I’m calling Body in the module M everywhere, I don’t understand how this can happen! If Body is already qualified by the time of the call, then when calling M:Body, M will be ignored. For example: ?- assertz(baz:a). true. ?- current_module(baz). true. ?- foo:b…

[image] pmoura: If Body is already qualified by the time of the call, then when calling M:Body , M will be ignored. Ah, I see, I have to check if that’s the problem. Thanks! (And I forgot to say that I thought your paper was very interesting and very clearly written. And I’m sorry if the answ…

[image] pmoura: If Body is already qualified by the time of the call, then when calling M:Body , M will be ignored. My admittedly sloppy investigation seems to indicate that Body isn’t qualified by the time of the call. Anything else I’m missing?

[image] anon95304481: But for the case of Torbjorn Lager receive, I would simply use meta_predicate directive this should work. But since Torbjorn Lager also requires a {_} wrapping you need somewhere a declaration: /* Additionally required since Torbjorn Lager passes receive argument wra…

[image] torbjorn.lager: If Body is already qualified by the time of the call, then when calling M:Body , M will be ignored. My admittedly sloppy investigation seems to indicate that Body isn’t qualified by the time of the call. Anything else I’m missing? I did this, but no change: receive…

How can the module for a term be identified?

Help!

pmoura November 27, 2019, 7:43pm 19

This clause is puzzling. It should simply be:

receive(Clauses) :-
    receive(Clauses, []).

Is there a meta_predicate tutorial?

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How can the module for a term be identified?

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