NAME Logic::Kleene - Kleene three-valued logic REQUIREMENTS This module requires Perl 5.6.0 or newer. Only core modules are used. INSTALLATION Installation can be done using the traditional Makefile.PL or the newer Build.PL method . Using Makefile.PL: perl Makefile.PL make test make install (On Windows platforms you should use nmake instead.) Using Build.PL (if you have Moddule::Build installed): perl Build.PL perl Build test perl Build install You may see warnings about undefined values during testing. This is normal. SYNOPSIS use logic::kleene; $a = !Kleene::Logic->new( somefunction() ); if ($a && $b) { ... } DESCRIPTION This module implements Kleene three-valued logic via overloading. The third value is between true and false, and is equivalent to an undefined value (as when a program has not yet returned a value). The significant different is that the negation of an undefined value is still undefined (and so treated as false). For example, my $status = Kleene::Logic->new(somefunction()); if (!$status) { print "somefunction failed"; } If the status value is false, then it will print the failure message, as expected. But if the status is undefined, then it will not print the message. REVISION HISTORY The following changes have been made since the last release: 0.04 - renamed to Logic::Kleene - cleaned up code a bit - better explanation of what the module does in documentation - more tests - overload "0+" - overload "cmp" and "<=>" AUTHOR Robert Rothenberg Suggestions and Bug Reporting Feedback is always welcome. Please use the CPAN Request Tracker at http://rt.cpan.org to submit bug reports. LICENSE Copyright (c) 2005 Robert Rothenberg. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.