# Even Fibonacci numbers

*Author: Mark A. Hershberger*

https://projecteuler.net/problem=2

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

Source code: prob002-hexmode.pl

use v6; # code exposes a bug in r34733 rakudo, but works in pugs class Fibonacci { has @!list = (0, 1); method next() { @!list[2] = [+] @!list; shift @!list; return @!list[1]; } } my $fibber = Fibonacci.new; my $f; my @r = gather { $f = $fibber.next; while $f < 4000000 { take (0+$f) if $f % 2 == 0; $f = $fibber.next; } } say [+] @r;