https://github.com/robrwo/perl-monads

Initial experiments with monads in Perl
https://github.com/robrwo/perl-monads

Last synced: 11 days ago
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Initial experiments with monads in Perl

• Host: GitHub
• URL: https://github.com/robrwo/perl-monads
• Owner: robrwo
• Created: 2011-10-09T12:16:28.000Z (about 13 years ago)
• Default Branch: master
• Last Pushed: 2014-03-10T23:09:10.000Z (over 10 years ago)
• Last Synced: 2024-10-11T21:56:34.802Z (about 1 month ago)
• Language: Perl
• Homepage:
• Size: 172 KB
• Stars: 5
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README
  • Changelog: Changes

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README

        
NAME

    Monad::Maybe - A quasi-implementation of the Maybe monad in Perl

VERSION

    Version 0.01

SYNOPSIS

      use Maybe::Monad;

      *suc = sub { Just(1 + shift) };

      $a = Just(10);

      $x->bind(\&suc);   # returns Just(11);

      *div = lift(sub { $_[0] / $_[1] });

      *add = lift(sub { $_[0] + $_[1] });

      $b = Just(0);

      $c = div($a, $b);  # $c is Nothing

      $d = add($c, $a);  # $d is Nothing

DESCRIPTION

    This is an experimental Perl implementation of a class with some

    properties of the Maybe monad.

  Methods

    nothing

          $x = Monad::Maybe->nothing;

        A constructor that returns "nothing".

    is_nothing

          if ($x->is_nothing) { ... }

        Returns true if the object is "nothing".

    just

          $x = Monad::Maybe->just( $scalar );

        A constructor that sets the value of the monad to "just" the

        argument.

        Note that

          Monad::Maybe->just( undef )

        returns "nothing".

    is_just

          if ($x->is_just) { ... }

        Returns true if the object is not "nothing".

    bind

          $x->bind( $f );

        Applies a function to the value of `$x', where `$f' is a function

        that takes a non-monad as an argument and returns a `Monad::Maybe'

        value.

        If the function does not return a `Monad::Maybe' object, or it

        returns an error, then it will return "nothing".

        If `$x' is nothing, then the `$f' is not actually run, and `bind'

        returns "nothing".

    join

          $x->join;

        Takes a `Monad::Maybe' of a `Monad::Maybe' and returns a

        `Monad::Maybe'.

        If `$x' is not a `Monad::Maybe' of a `Monad::Maybe', then it returns

        "nothing".

  Subroutines

    Nothing

          $x = Nothing;

        Shorthand for the nothing constructor.

    Just

          $x = Just( $v );

        Shorthand for the just constructor.

    lift

          $g = lift( $f );

        Lifts a non-monadic function to a `Monad::Maybe' function.

        If any of the values passed to the lifted function are "nothing",

        then `$f' is not actually executed, and `$g' returns "nothing".

        If `$f' dies, then `$g' returns "nothing".

CAVEATS

    This is an experimental module. The interface may change completely.

SEE ALSO

    Data::Monad

    https://gist.github.com/peczenyj/9445226

AUTHOR

    Robert Rothenberg, `'

LICENSE AND COPYRIGHT

    Copyright 2011-2014 Robert Rothenberg.

    This program is free software; you can redistribute it and/or modify it

    under the terms of either: the GNU General Public License as published

    by the Free Software Foundation; or the Artistic License.

    See http://dev.perl.org/licenses/ for more information.