Prolog: Code Generation

Question

What's the most idiomatic approach to output prolog code from a prolog program (as a side effect)?

For instance, in a simple case, I might want to write a Program that, given a text input, yields another Prolog program representing the text as a directed graph.

I understand this question is somewhat vague, but I've resigned to consulting Stackoverflow after failing to find a satisfying answer in the available Prolog Meta-Programming literature, which mostly covers applications of meta-circular interpreters.

If you feel this question might be better articulated some other way, please edit it or leave a comment.

At the very least, give a concrete example of the text input and the Prolog representation you want as output. A non-idiomatic approach that does that would also improve your question. — user1812457
Generate the rules, assert them and use "listing/1" or similar: swi-prolog.org/pldoc/man?section=listing — pasaba por aqui
Did you do some progress ? I'm also interested in automated code generation in Prolog (Ergo/Flora preferrably), but on mainstream languages (C++,..) Did you do some tries in area of code synthesis on hypergraph networks (opencog/hypergraphdb) ? — Dmitry Ponyatov
@DmitryPonyatov Unfortunately, I haven't had time to do much Prolog recently! Your work sounds really interesting. — David Shaked

mat mat · Accepted Answer · 2016-09-03T07:35:51

The most idiomatic way is always to stay pure and avoid side effects.

Let the toplevel do the writing for you!

To generate a Prolog program, you define a relation that says for example:

program(P) :- ...

and then states, in terms of logical relations, what holds about P.

For example:

program(P) :-
        P = ( Head :- Body ),
        Head = head(A, B),
        Body = body(A, B).

Example query and answer:

?- program(P).
P =  (head(_G261, _G262):-body(_G261, _G262)).

So, there's your program, produced in a pure way.

If you want to write it, use portray_clause/1:

?- program(P), portray_clause(P).
head(A, B) :-
        body(A, B).
...

This can be useful in a failure driven loop, to produce many programs automatically.

Prolog: Code Generation

2 Answers