#!/usr/bin/ruby # ## https://rosettacode.org/wiki/Primality_by_trial_division # func is_prime(a) { given (a) { when (2) { true } case (a <= 1 || a.is_even) { false } default { range(3, a.sqrt) -> any { .divides(a) } -> not } } } 25.times { |i| is_prime(i) && say i; }