and now for something entirely different..

just as an aside, using map in a void context (i.e. not returning anything), is generally considered a BadThing(TM). If you are simply looking for a way to do simple single line loops, you can always use for().. ala

print "before: $_\n" for @instances;
screwed "$_"         for @instances;
print "after: $_\n"  for @instances;
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You might already know this, you might not, but I figured I would toss it out there. The reason it't not so good, is Perl can go through a lot of trouble to build a list of things to return from the map block, and if you don't use them its simply a waste of processor time and memory that could be better spent doing other things.

use perl;