module AplMode =
  let (%) l n = List.map (fun v -> v % n) l
  let (=) l b = List.map (fun v -> v = b) l
  let (||) l1 l2 = List.zip l1 l2 |> List.map (fun (a, b) -> a || b)
  let (~+) l = List.reduce (+) l

  type List<'T> with 
    member x.Item with get(a) = List.zip a x |> List.filter fst |> List.map snd

open AplMode
let w = [1..999]

// See: http://theburningmonk.com/2015/07/apl-solving-euler-problem-1/
+(w.[w%3=0||w%5=0])