in reply to do not understand grep example

Forget about the grep for a while and just get straight in your head how the digit_sum_is_odd function works and what it does.

use Test::More tests => 14; sub digit_sum_is_odd { my $input = shift; my @digits = split //, $input; my $sum; $sum += $_ for @digits; return $sum % 2; } ok digit_sum_is_odd(1); ok not digit_sum_is_odd(2); ok digit_sum_is_odd(3); ok digit_sum_is_odd(9); ok digit_sum_is_odd(10); ok not digit_sum_is_odd(11); ok digit_sum_is_odd(12); ok not digit_sum_is_odd(13); ok digit_sum_is_odd(1000000); ok not digit_sum_is_odd('pony'); ok digit_sum_is_odd('pony1'); ok digit_sum_is_odd(3, 4); ok digit_sum_is_odd(3, 5); ok digit_sum_is_odd(3, 'chimpanzee', 'monkey', 'baboon');
perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'