The syntax of sort can't be replicated by subs.

>perl -E"say defined(prototype('CORE::sort')) ? 'can replicate' : 'can
+\'t replicate'"
can't replicate
[download]

The best you can do is &@.

sub mysort(&@) {
   my $code_ref = shift;
   ...
}

mysort { ... } ...      # Same as: mysort(sub { ... }, ...)
[download]