http://www.perlmonks.org?node_id=46938


in reply to Back to Remedial Perl for Me: map{} function

A note on efficiency:

`map EXPR, LIST' is in general quite a bit faster than `map BLOCK LIST', so you should probably try to use EXPRs rather than BLOCKs whenever possible in a map.

For instance, here are your first examples recoded as EXPRs:

my @adjusted_array = map $_ * 10, @array;

my %hash = map split /-/, @array;

Why is it faster? Using the BLOCK introduces a new scope, which adds some extra ops and time to start and finish. BLOCKs do give you extra power and flexibility, but try to use them only when necessary.

-dlc