There has been some recent discussions about the virtues of map vs. foreach ("advanced" Perl functions and maintainability). The perldoc for map indicates that they are pretty much the same. I did the following comparison in terms of their performance: 
use strict;
use Benchmark qw(:all);
timethese(1000,{
    "Foreach" => sub{ my %hash = map{$_=>1} (1..10000);},
    "Map" => sub{ my %hash; $hash{$_} = 1 foreach (1..10000);}
   })

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I got the following: 
Benchmark: timing 1000 iterations of Foreach, Map...
   Foreach: 54 wallclock secs (49.54 usr +  0.12 sys = 49.66CPU) @ 20.
+14/s (n=1000)
       Map: 31 wallclock secs (28.80 usr +  0.06 sys = 28.86CPU) @ 34.
+65/s (n=1000)

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So it seems map is faster, or I'm doing something incorrect?

Note: Oops, as pointed out by ikegami, my Map and Foreach are reversed. I'll leave it as is, so not to confuse the comments. Thanks.

In reply to performance of map vs. foreach by johnnywang

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