Even Fibonacci numbers
Author: Gerhard R
https://projecteuler.net/problem=2
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with three terms 1, 1, and 2, the first 10 terms will be:
1, 1, 2, 3, 5, 8, 13, 21, 34, 55 ...
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-gerdr.pl
use v6; say [+] grep * %% 2, (1, 1, *+* ...^ * > 4_000_000);