use strict;
use warnings;

use YAML::Syck qw(LoadFile;

# slurp all arguments
my @letters = split //, @ARGV;
die usage unless @letters;
my $key = join '', sort @letters;
my $lookup_word = LoadFile('dict.yml');
if ( exists $lookup_word->{$key} ) {
    my @words = sort @{ $lookup_words{$key} };
    print "Found words: @words\n;
}
else {
    print "No words found\n";
}

sub usage {
...
}