use strict;
use warnings;
use Lingua::StopWords qw(getStopWords);

{
    open my $infile, '<fulltext.txt' or die $!;
    my $fulltext = do { local $/; <$infile> };

    $fulltext =~ s/ *?\b$_\b *?//gi for keys %{ getStopWords('en') };

    open my $outfile, '>nostopwords.txt' or die $!;
    print $outfile $fulltext;
}