sub ro_map (&@){
	my $sub=shift;
  	my @return;
  	foreach (@_) {
	    local $_=$_;
	    push @return,$sub->();
  	}
  	@return
}
my @out=ro_map{s/x/y/g}@in;
print "original: @in\n";
print "changed : @out\n";