boolean - Boolean support for Perl

       Ingy döt Net <ingy@cpan.org>

       Copyright 2007-2016. Ingy döt Net.

       This program is free software; you can redistribute it and/or modify it under  the  same  terms  as  Perl
       itself.

       See <http://www.perl.com/perl/misc/Artistic.html>

perl v5.36.0                                       2022-10-13                                       boolean(3pm)

       This module offered an export tag, "-truth", that overrides the Perl interpreter's  internal  values  for
       true  and  false.  This  has  been  found  to  corrupt the interpreter in some circumstances. Also, these
       overrides will no longer be possible as of Perl 5.22. Therefore, the "-truth" import tag is deprecated.

       Most programming languages have a native "Boolean" data type. Perl does not.

       Perl has a simple and well known Truth System. The following scalar values are false:

           $false1 = undef;
           $false2 = 0;
           $false3 = 0.0;
           $false4 = '';
           $false5 = '0';

       Every other scalar value is true.

       This module provides basic Boolean support, by defining two special objects: "true" and "false".

       This module defines the following functions:

       "true"
           This  function  returns  a scalar value which will evaluate to true. The value is a singleton object,
           meaning there is only one "true" value in a Perl process at any time. You can check  to  see  whether
           the value is the "true" object with the isTrue function described below.

       "false"
           This  function  returns a scalar value which will evaluate to false. The value is a singleton object,
           meaning there is only one "false" value in a Perl process at any time. You can check to  see  whether
           the value is the "false" object with the isFalse function described below.

       "boolean($scalar)"
           Casts  the scalar value to a boolean value. If $scalar is true, it returns "boolean::true", otherwise
           it returns "boolean::false".

       "isTrue($scalar)"
           Returns  "boolean::true"  if  the  scalar  passed  to  it  is  the  "boolean::true"  object.  Returns
           "boolean::false" otherwise.

       "isFalse($scalar)"
           Returns  "boolean::true"  if  the  scalar  passed  to  it  is  the  "boolean::false"  object. Returns
           "boolean::false" otherwise.

       "isBoolean($scalar)"
           Returns "boolean::true" if the scalar passed to it is the "boolean::true" or "boolean::false" object.
           Returns "boolean::false" otherwise.

       JSON::MaybeXS (or less preferably JSON.pm ) will encode Perl data with boolean.pm values correctly if you
       use the "convert_blessed" option:

           use JSON::MaybeXS;
           use boolean -truth;
           my $json = JSON::MaybeXS->new->convert_blessed;
           say $json->encode({false => (0 == 1)});     # Says: '{"false":false}',

       Since true and false return objects, you can call methods on them.

       "$boolean->isTrue"
           Same as isTrue($boolean).

       "$boolean->isFalse"
           Same as isFalse($boolean).

       boolean - Boolean support for Perl

       When sharing data between programming languages, it is important to support the same group of basic
       types. In Perlish programming languages, these types include: Hash, Array, String, Number, Null and
       Boolean. Perl lacks native Boolean support.

       Data interchange modules like YAML and JSON can now "use boolean" to encodedecoderoundtrip Boolean
       values.

           use boolean;

           do &always if true;
           do &never if false;

           do &maybe if boolean($value)->isTrue;

       and:

           use boolean ':all';

           $guess = int(rand(2)) % 2 ? true : false;

           do &something if isTrue($guess);
           do &something_else if isFalse($guess);

       By default this module exports the "true", "false" and "boolean" functions.

       The module also defines these export tags:

       ":all"
           Exports "true", "false", "boolean", "isTrue", "isFalse", "isBoolean"

       This document describes boolean version 0.46.