How do I include a .pl file in Prolog?

Question

I'd like to include code from another source file. Does anyone know how to do that?

Answer 1

If you want to include the file literally - similar to #include, use :- include('file.pl').

Most of the time it is preferable to structure your program using modules, though.

Answer 2

If your file is called foo.pl, you can include it using

:- [foo].

or, equivalently and a bit more explicit

:- consult(foo).

or, if you're worried it may be loaded several times in a larger app

:- ensure_loaded(foo).

or, if you're using full-blown modules

:- use_module(foo).

though the exact name of the last predicate differs between Prolog versions.