=head1 NAME

Lingua::EN::PluralToSingular - change an English plural to a singular

=head1 SYNOPSIS

    use Lingua::EN::PluralToSingular 'to_singular';

    print to_singular ('knives');
    # "knife"

    use Lingua::EN::PluralToSingular 'is_plural';

    # Returns 1
    is_plural ('sheep');
    # Returns 0
    is_plural ('dog');
    # Returns 1
    is_plural ('dogs');
    # Returns 0
    is_plural ('cannabis');
    

=head1 DESCRIPTION

This converts words denoting a plural in the English language into
words denoting a singular noun.

=head1 FUNCTIONS

=head2 to_singular

    my $singular = to_singular ($word);

Convert C<$word> into its singular form. For example,

    to_singular ('cats')

returns 'cat'. If the word is unknown or does not seem to be
plural, C<to_singular> returns the word itself, so

    to_singular ('battlehorn');

returns 'battlehorn'.

=head2 is_plural

    if (is_plural ($word)) {
        print "There are too many $word here.\n";
    }
    else {
        print "There is a $word here.\n";
    }

Returns 1 if the word is a valid plural, 0 if not. It also returns 1
for ambiguous words like "sheep".

=head1 LIMITATIONS

=head2 Assumes the input is a noun

L</to_singular> assumes its input is a noun. For example, "lives" may
be the plural of "life", or the verb "live", as in "he lives". The
routine assumes a noun and converts to "life".

=head2 Distinguishes lower and upper case

It does not deal with capitalized words. If the input word may be
capitalized, or if its initial letter may be capitalized, the user
must preprocess it to put it into the normal case. So, for example,

    to_singular ('FLIES');

returns 'FLIES' and

    to_singular ('Wolves');

returns 'Wolve'. Similarly,

    to_singular ('Charles');

returns 'Charles', but 

    to_singular ('charles');

returns 'charle', since the exception only applies if the word is
capitalized.

=head2 Does not handle pronouns

The module does not attempt to handle pronoun forms like "ourselves"
or "themselves". These words are left unaltered.

=head1 STANDALONE SCRIPT

The script F<scripts/singular> provides a quick way to get singular
versions of nouns:

    singular cats dogs geese
    # Prints "cat dog goose".

=head1 BUGS

This module is in development, and there are many exceptions which are
not included yet.

=head1 ACKNOWLEDGEMENTS

Thanks to Xan Charbonnet and H2CHANG for various additions and fixes.

=head1 AUTHOR

Ben Bullock, <bkb@cpan.org>

=head1 COPYRIGHT & LICENCE

This package and associated files are copyright (C) 2012-2014 Ben
Bullock.

You can use, copy, modify and redistribute this package and associated
files under the Perl Artistic Licence or the GNU General Public
Licence.


