IN: fibo USING: kernel math math.parser io sequences locals ; : next-fibo ( x y -- y x+y ) swap over + ; foldable flushable inline :: fibo-max ( max -- seq ) 1 1 [ next-fibo over max <= ] [ over ] produce 2nip ; foldable flushable : even-fibo-sum ( max -- sum ) fibo-max [ even? ] filter sum ; : print-euler2 ( -- ) 4000000 even-fibo-sum number>string print ; MAIN: print-euler2