I've been trying to grok the perlfunc:map function too-- and this was encouragement to dig deeper, so I decided to play with it. I tried rewriting it using lower-level functions. I came up with the following, which in all the minimal testing I did seemed to reproduce the results of map. I even used a $function which was more complex and returned multiple elements for some items in the original list. This helped me get a way of thinking about the command (and hopefully it's a good way to think about it), so I thought I'd share.

use strict;

my @start_list = (qw/ one two three four five six /);
my $function = sub { uc };

my @end_list = fake_map( $function, @start_list );
#equivalent to @end_list = map { &$function } @start_list;

my %end_hash = fake_map( $function, @start_list );
#equivalent to %end_hash = map { &$function } @start_list;

print (join (' ', @end_list, "\n") );
foreach (keys %end_hash) {
  print "hash{'$_'} = $end_hash{$_}\n";
}

sub fake_map {
  my $func = shift;
  my @instack = @_;
  my @outstack = ();
  foreach (@instack) {
    push (@outstack, &$func);
  }
  return @outstack;
}
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