sidef/scripts/RosettaCode/luhn_test_of_credit_card_numbers.sf

#!/usr/bin/ruby

func luhn (n) {
    var chars = n.to_s.reverse.split(1).map{.to_i};
    var (i, sum) = (0, 0);
    static a = (0..9 -> map {|j| (2*j / 10 -> int) + (2*j % 10 -> int) });
    chars.each { |j|
        sum += (i++.is_odd ? a[j] : j);
    };
    return (sum % 10 == 0);
}

# Test and display
[49927398716, 49927398717, 1234567812345678, 1234567812345670].each { |n|
    say [n, luhn(n)].dump;
}