# By considering the terms in the Fibonacci sequence whose values do not
# exceed four million, find the sum of the even-valued terms.
# https://projecteuler.net/problem=2

[1 2]

[[a b]: a b a b +] [fib-once] def

[4 1000 * 1000 *] [4_million] def

[dup last 4_million gt?] [[fib-once] doin] while

[even?] filter

[dup length 1 lt?] [[+] doin] while

unquote println