NAME
Language::Prolog::Sugar - Syntactic sugar for Prolog term constructors
SYNOPSIS
use Language::Prolog::Sugar vars => [qw(X Y Z)];
use Language::Prolog::Sugar functors =>{ equal => '=',
minus => '-' };
use Language::Prolog::Sugar functors =>[qw(is)];
use Language::Prolog::Sugar atoms =>[qw(foo bar)];
use Language::Prolog::Sugar atoms =>{ cut => '!' };
use Language::Prolog::Sugar chains =>{ andn => ',',
orn => ';' };
$term=andn( equal(X, foo),
orn( equal(Y, [4, bar]),
equal(Y, foo)),
cut,
is(Z, minus(34, Y)));ABSTRACT
This module allows you to easily define constructor subs for Prolog terms.
DESCRIPTION
Language::Prolog::Sugar is able to export to the calling package a set of subrutines to create Prolog terms as defined in the Language::Prolog::Types module.
Perl programs using these constructors have the same look as real Prolog programs.
Unfortunately Prolog operators syntax could not be simulated in any way I know (well, something could be done using overloading, but just something).
EXPORT
Whatever you wants!
Language::Prolog::Sugar can create constructors for four Prolog types: atoms, functors, vars and chains.
The syntax to use it is as follows:
use Language::Prolog::Sugar $type1s=>{ $name1 => $prolog_name1,
$name2 => $prolog_name2,
... },
...or
use Language::Prolog::Sugar $type2s=>[qw($name1 $name2 ...)],
...$type1s, $type2s, ... are atoms, functors, vars or chains.
$name1, $name2, ... are the names of the subrutines exported to the caller package.
$prolog_name, $prolog_name2, ... are the names that the constructors use when making the Prolog terms.
i.e:
use Language::Prolog::Sugar atoms=>{ cut => '!' }exports a subrutine cut that when called returns a Prolog atom !.
use Language::Prolog::Sugar functor=>{ equal => '=' }exports a subrutine equal that when called returns a Prolog functor =.
equal(3,4)returns
'='(3,4)It should be noted that functor arity is inferred from the number of arguments:
equal(3, 4, 5, 6, 7)returns
'='(3, 4, 5, 6, 7)I call 'chain' the structure formed tipically by ','/2 or ';'/2 operators in Prolog programs. i.e., Prolog program
p, o, r, s.is actually
','(p, ','(o, ','(r, s))).using chains allows for a more easily composition of those structures:
use Language::Prolog::Sugar chains => { andn => ',' },
atoms => [qw(p o r s)];and
andn(p, o, r, s)generates the Prolog structure for the example program above.
Also, the tag auto_term can be used to install and AUTOLOAD sub on the caller module that would make a functor, term or variable for every undefined subroutine. For instance:
use Language::Prolog::Sugar 'auto_term';
swi_call(use_module(library(pce)));
swi_call(foo(hello, Hello))The old auto_functor tag has been obsoleted.
SEE ALSO
Language::Prolog::Types, Language::Prolog::Types::Factory
COPYRIGHT AND LICENSE
Copyright 2002-2006 by Salvador Fandiño (sfandino@yahoo.com).
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.