# This is a fairly useless function which is basically
# just a copy of grep which enforces numeric context
# on the list items...
#
sub filter_nums (&@)
{
  my $coderef = shift;
  return
    grep { $coderef->() }
    map  { 0 + $_ }
    @_
}

my @even = filter_nums { not($_ % 2) } qw(1 2 3 4 potato);