pipe (FROM_CHILD, TO_PARENT) or die "Oops Pipe: $!\n";
pipe (FROM_PARENT, TO_CHILD) or die "Oops Pipe: $!\n";
select((select(TO_CHILD),  $|++ )[0]); # set autoflush
select((select(TO_PARENT), $|++ )[0]); # set autoflush

my @values = qw( value1 value2 value3 );

print "Before forking \@values:\n";
print "$_\n" for @values;

for my $value (@values) {
    print "\nLoop value $value\n";
    # let's fork
    if ( my $pid = fork ) {
        # this is parent
        print TO_CHILD "$value\n";  # send $value to child
        chomp( my $child_says = <FROM_CHILD> );
        print "Child says '$child_says' to parent\n";
        $value = $child_says; # change $value and thus @values for parent
        waitpid( $pid, 0 );
    } else {
        # this is child
        die "Can't fork: $!\n" unless defined $pid;
        chomp( my $parent_says = <FROM_PARENT> );
        print "Parent says '$parent_says' to child\n";
        print TO_PARENT "Child pid $$ replies '$parent_says'\n";
        exit;
    }
}

close FROM_CHILD; close TO_CHILD;
close FROM_PARENT; close TO_PARENT;

print "\nAfter forking \@values:\n";
print "$_\n" for @values;