Hello fellow monks!
After a long ( and now semi permanent ) exile from computing I present a subroutine which will populate an array with all possible case permutations of a word which is supplied to it. I consider it an elegant solution to something which originally was a recursive broken monstrosity.

Recursion is evil.

sub casify
{
my @arr = ();
my $word =lc $_[0];
my $maxcombos = 2**(length $word) - 1;

foreach $n ( 0..$maxcombos )
{
# convert number from being stringified, to being a u_short, and then 
+into binary
   $_ = unpack( 'b*', pack('s',$n) );

   tr/1/_/;            # uppercase ones
   tr/0/\377/;        # leave zeros alone
   $result = "$word" & $_; # string AND
   push( @arr, $result ) ;
}

return @arr;
}

#--------------------------------------------------
# fast casify(), first arg word ref, second arg arr ref

sub casify_fast
{

foreach $n ( 0..(2**(length ${$_[0]}) - 1) )
{
# convert number from being stringified, to being a u_short, and then 
+into binary
   
   $_ = unpack( 'b*', pack('s',$n) );

   tr/10/_\377/;

   push( @{$_[1]}, ("${$_[0]}" & $_) ) ;    # string AND them, ones up
+percase the letters, zeros don't
}
return;
}

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In reply to upper-lower case combinatorics by bl0rf

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