Question

In Scheme you can iterate over multiple lists in with for-each:

> (for-each (lambda (a b) (display (+ a b)) (newline)) '(10 20 30) '(1 2 3))
11
22
33
> 

I know that in Perl you can use for to iterate over a single list. What’s a good way to iterate over multiple lists as in the Scheme example?

I’m interested in answers for Perl 5 or 6.

Answer 1

In Perl 5 you can use the module List::MoreUtils. Either with pairwise or with the iterator returned by each_array (which can take more than two arrays to iterate through in parallel).

use 5.12.0;
use List::MoreUtils qw(pairwise each_array);

my @one = qw(a b c d e);
my @two = qw(q w e r t);

my @three = pairwise {"$a:$b"} @one, @two;

say join(" ", @three);

my $it = each_array(@one, @two);
while (my @elems = $it->()) {
    say "$elems[0] and $elems[1]";
}