sub sumTo {
   return 0 if $_[0] == 0 && @_ > 1;
   _sumTo(@_);     # or &_sumTo if you want to be cryptic
}

sub _sumTo {
   my ($target, @list) = @_;
   return 1 if $target == 0;
   return 0 if @list == 0;
   # here goes the recursive call to _sumTo
}