#! 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 11;

print for grep defined(), $s =~ /^$re2$/;

__END__
C:\test>junk
could
someone
recommend
a
working
perl
module
to
split
concatenated
words

##</code><code>##

C:\test>junk
could
someone
recommend
aw
or
king
perl
module
to
split
concatenated
words