Syntax::Keyword::Junction

Section: User Contributed Perl Documentation (3)
Updated: 2014-07-07
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NAME

Syntax::Keyword::Junction - Perl6 style Junction operators in Perl5

VERSION

version 0.003008

SYNOPSIS

  use Syntax::Keyword::Junction qw/ all any none one /;

  if (any(@grant) eq 'su') {
    ...
  }

  if (all($foo, $bar) >= 10) {
    ...
  }

  if (qr/^\d+$/ == all(@answers)) {
    ...
  }

  if (all(@input) <= @limits) {
    ...
  }

  if (none(@pass) eq 'password') {
    ...
  }

  if (one(@answer) == 42) {
    ...
  }

or if you want to rename an export, use Sub::Exporter options:

  use Syntax::Keyword::Junction any => { -as => 'robot_any' };

  if (robot_any(@grant) eq 'su') {
    ...
  }

DESCRIPTION

This is a lightweight module which provides 'Junction' operators, the most commonly used being "any" and "all".

Inspired by the Perl6 design docs, <http://dev.perl.org/perl6/doc/design/exe/E06.html>.

Provides a limited subset of the functionality of Quantum::Superpositions, see ``SEE ALSO'' for comment.

Notice in the ``SYNOPSIS'' above, that if you want to match against a regular expression, you must use "==" or "!=". Not "=~" or "!~". You must also use a regex object, such as "qr/\d/", not a plain regex such as "/\d/".

SUBROUTINES

all()

Returns an object which overloads the following operators:

  '<',  '<=', '>',  '>=', '==', '!=',
  'lt', 'le', 'gt', 'ge', 'eq', 'ne',
  '~~'

Returns true only if all arguments test true according to the operator used.

any()

Returns an object which overloads the following operators:

  '<',  '<=', '>',  '>=', '==', '!=',
  'lt', 'le', 'gt', 'ge', 'eq', 'ne',
  '~~'

Returns true if any argument tests true according to the operator used.

none()

Returns an object which overloads the following operators:

  '<',  '<=', '>',  '>=', '==', '!=',
  'lt', 'le', 'gt', 'ge', 'eq', 'ne',
  '~~'

Returns true only if no argument tests true according to the operator used.

one()

Returns an object which overloads the following operators:

  '<',  '<=', '>',  '>=', '==', '!=',
  'lt', 'le', 'gt', 'ge', 'eq', 'ne',
  '~~'

Returns true only if one and only one argument tests true according to the operator used.

ALTERING JUNCTIONS

You cannot alter junctions. Instead, you can create new junctions out of old junctions. You can do this by calling the "values" method on a junction.

 my $numbers = any(qw/1 2 3 4 5/);
 print $numbers == 3 ? 'Yes' : 'No';   # Yes

 $numbers = any( grep { $_ != 3 } $numbers->values );
 print $numbers == 3 ? 'Yes' : 'No';   # No

You can also use the "map" method:

 my $numbers = any(qw/1 2 3 4 5/);
 my $prime   = $numbers->map( \&is_prime );

 say for $prime->values; # prints 0, 1, 1, 0, 1

EXPORT

'all', 'any', 'none', 'one', as requested.

All subroutines can be called by its fully qualified name, if you don't want to export them.

  use Syntax::Keyword::Junction;

  if (Syntax::Keyword::Junction::any( @questions )) {
    ...
  }

WARNING

When comparing against a regular expression, you must remember to use a regular expression object: "qr/\d/" Not "/d/". You must also use either "==" or "!=". This is because "=~" and "!~" cannot be overridden.

TO DO

Add overloading for arithmetic operators, such that this works:

  $result = any(2,3,4) * 2;

  if ($result == 8) {...}

AUTHORS

•: Arthur Axel ``fREW'' Schmidt <frioux+cpan@gmail.com>
•: Carl Franks

COPYRIGHT AND LICENSE

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.