Perl's sort comparison function is sort of based on C's sort comparison function.

The only thing that Perl's sort requires is that the function returns a negative number, zero or a positive number. You can use the <=> or cmp operators or any other method you choose.

Update:

For example:

$ perl -MList::Util=shuffle -le'
my @x = shuffle 1 .. 20;
print "@x";
my @y = sort { $a <=> $b } @x;
print "@y";
my @z = sort { $a - $b } @x;
print "@z"
'
7 10 16 20 14 15 4 18 19 17 6 5 8 9 2 13 1 3 11 12
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

$ perl -MList::Util=shuffle -le'
my @x = shuffle -10 .. 10;
print "@x";
my @y = sort { $a <=> $b } @x;
print "@y";
my @z = sort { $a - $b } @x;
print "@z"
'
-1 -7 -4 1 4 -9 10 -3 0 -8 -6 -2 8 -10 5 6 9 -5 2 3 7
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
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