turtle-lang 0.1.1

A humble, fun, and friendly Lisp
Documentation 
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;; From 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.

(import "@prelude")
(import "@math" :math)

(let 'p2 0)
(let 'p1 1)

(let 'answer ,
    (append
        '(sum) 
        (filter 
            (lambda '(k) '(eq (modulo k 2) 0)) 
            (math::fibonacci 33))))

(assert 
    (eq answer 4613732))