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 <rrwo at cpan.org>

  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.