I don't think i have seen this one yet, although it is close in spirit to demerphq's solution:

use strict;
no warnings;

my @array = reverse 'a' .. 'j';
my $var   = shift() - 1;

print join '', reverse @array[0..$var];
[download]

Update: one-liner for the heck of it

perl -le"@_=reverse a..j;print join'',reverse@_[0..shift()-1]" 5
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)