#!/usr/local/bin/perl -lw

open(PERL, "/usr/share/dict/words");
while (<PERL>) {
    chomp;
    /^([perl])/i or next;
    push @{lc($1)}, $_;
}
perl([], split //, "perl");
sub perl {
    my $perl = shift;
    my $letter = shift;
    for (@$letter) {
        perl([@$perl, $_], @_);
    }
    print join " ", @$perl;
}