#! perl -slw
use strict;

my @w = do{ local @ARGV = 'words.txt'; <> };
chomp @w;

my $s = 'couldsomeonerecommendaworkingperlmoduletosplitconcatenatedwords';

my @subset = grep{ $s =~ /$_/ } 'a', 'perl', @w;

my $re1 = join '|', sort{ length( $b ) <=> length( $a ) }@subset;
my $re2 = "($re1)?" x 20;

my @found = $s =~ /^$re2$/;

print join '|', @found;

my @undefsRemoved = grep defined(), @found;

print for @undefsRemoved;

##</code><code>##

c:\test>junk
Use of uninitialized value $found[12] in join or string at C:\test\junk.pl line 15, <> line 178691.
Use of uninitialized value $found[13] in join or string at C:\test\junk.pl line 15, <> line 178691.
Use of uninitialized value $found[14] in join or string at C:\test\junk.pl line 15, <> line 178691.
Use of uninitialized value $found[15] in join or string at C:\test\junk.pl line 15, <> line 178691.
Use of uninitialized value $found[16] in join or string at C:\test\junk.pl line 15, <> line 178691.
Use of uninitialized value $found[17] in join or string at C:\test\junk.pl line 15, <> line 178691.
Use of uninitialized value $found[18] in join or string at C:\test\junk.pl line 15, <> line 178691.
Use of uninitialized value $found[19] in join or string at C:\test\junk.pl line 15, <> line 178691.
could|someone|recommend|aw|or|king|perl|module|to|split|concatenated|words||||||||

##</code><code>##

my @undefsRemoved = grep defined(), @found;