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Pack function_expansion -- prolog/readme.txt


:- use_module(library(function_expansion)).
user:function_expansion(incr(N), X, X is N+1).
main :-
    format('After 2 comes ~p~n', [incr(2)]).


Prolog doesn't offer function syntax. Anything one can do with functions, she can do with predicates. The syntax is a little verbose because it requires an auxiliary variable.

For example, one might approximate pi:

main :-
    format('pi is roughly ~p~n', [Pi]).

It's often obnoxious to think up a name for an auxiliary variable. function_expansion/3 lets you write macros so that pi can be included directly in format's arguments. Auxiliary variables are generated for you at compile time.

Repository available on GitHub: https://github.com/mndrix/function_expansion


Using SWI-Prolog 6.3 or later:

$ swipl
1 ?- pack_install(function_expansion).