NAME
Language::Prolog::Types - Prolog types in Perl.
SYNOPSIS
use Language::Prolog::Types::overload;
use Language::Prolog::Types qw(:ctors);
$atom=prolog_atom('foo');
$list=prolog_list(1,2,3,4,5);
$functor=prolog_functor('foo',1,2,3,'bar');
$nil=prolog_nil;
use Language::Prolog::Types qw(:is);
print "$atom is an atom\n" if prolog_is_atom($atom);
print "$list is a list\n" if prolog_is_list($list);
print "$nil is nil\n" if prolog_is_nil($nil);
use Language::Prolog::Types qw(:short);
$atom=A('foo');
$list=L(1,2,3,4);
$functor=F('foo',1,2,3,'bar')
print "$atom is an atom\n" if isA($atom);
print "$list is a list\n" if isL($list);
print "$nil is nil\n" if isN($nil);
ABSTRACT
Language::Prolog::Types is a set of modules implementing Prolog types in Perl.
DESCRIPTION
This module exports subroutines to create Prolog terms in Perl, to test term types and also some utility functions to convert data between Prolog and Perl explicitly.
You will see that there is not any kind of constructor for Prolog atoms, this is because Perl scalars (numbers or strings) are directly used as Prolog atoms.
You can also use Perl list references as Prolog lists, and Perl undef
as Prolog nil ([]
).
EXPORT_TAGS
Subroutines are grouped in three tags:
:is
-
Subroutines to test typing of terms.
prolog_is_atom($term)
-
true if
$term
is a valid Prolog atom (Perl number or string). prolog_is_nil($term)
-
true if
$term
is Prolog nil[]
. Perl undef is equivalent to Prolog nil. prolog_is_list($term)
-
true if
$term
is Prolog list.It should be noted that Prolog nil although represented with the empty list
[]
is not a list. prolog_is_list_or_nil($term)
-
true if
$term
is a Prolog list or nil. prolog_is_functor($term)
-
true if
$term
is a Prolog functor.It should be noted that list are formed with the functor '.'/2.
prolog_is_variable($term)
prolog_is_var($term)
-
true if
$term
is a Prolog variable. prolog_is_ulist($term)
-
true if
$term
is a Prolog unfinished list (those whose tail is not nil). prolog_is_string($term)
-
true if
$term
can be converted to a string, a list whose elements are integers in the range [0..255].
:ctors
-
Subruotines to create new Prolog terms.
prolog_list(@terms)
-
returns a new prolog list with elements
@terms
. prolog_ulist(@terms, $tail)
-
returns a new prolog unfineshed list with elements
@terms
and tail$tail
. prolog_functor($name, @args)
-
returns a new prolog functor which name
$name
and arguments@args
. prolog_variable($name)
prolog_var($name)
-
returns a new prolog variable with name
$name
. prolog_atom($atom)
-
As normal Perl strings and numbers are used to represent Prolog atoms this function only ensures that its argument is properly converted to a string.
prolog_nil()
-
returns Prolog nil (
[]
). prolog_string($string)
-
returns Prolog string, that is a list with the ASCII codes of
$string
. prolog_chain($ftr, $term1, $term2, ..., $termn, $termo)
-
creates prolog structure
$ftr($term1, $ftr($term2, $ftr($term3, $ftr(... $ftr($termn, $termo) ... ))))
it should be noted that
prolog_chain($ftr, $term)
returns
$term
prolog_opaque($object)
-
creates a proxy opaque object to tell Perl to pass the object to Prolog as an opaque reference that can not be directly used from Prolog but just passed back to Perl in callbacks.
:util
-
Subroutines to convert Prolog data to Perl.
prolog_list2perl_list($term)
-
converts a Prolog_list to a Perl array acounting for all the different possibilities of Prolog list representations.
prolog_list2perl_string($term)
-
converts a Prolog list to a Perl string. All the elements in the list have to be integers in the range [0..255] or an exception will be raised.
:short
-
For the lazy programmer,
:short
includes a set of abreviations for the:is
and:ctors
groups:
SEE ALSO
Language::Prolog::Types::overload
COPYRIGHT AND LICENSE
Copyright 2002-2005, 2007 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.