Actually, a naïve merge sort is dead simple. Quite possibly the easiest to explain, too. 
sub mergesort {
   return $_[0] if @_ == 1;

   my $i = int( @_ / 2 );
   my @a = mergesort(@_[0..$i-1]);
   my @b = mergesort(@_[$i..$#_]);

   my @sorted;
   while (@a && @b) {
      if    ($a[0] < $b[0]) { push @sorted, shift(@a);            }
      elsif ($b[0] < $a[0]) { push @sorted, shift(@b);            }
      else                  { push @sorted, shift(@a), shift(@b); }
   }

   return ( @sorted, @a, @b );
}

[download]

lol! I got two 5.8.8 question this week. It'll be a while before it's ok to be sick of 5.14.

In reply to Re^5: Numeric sorting WITHOUT <=> by ikegami
in thread Numeric sorting WITHOUT <=> by Anonymous Monk

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