Elm on the command line

IsEven.elm

module IsEven exposing (output)

import List

getFirstArg : List String -> String
getFirstArg list =
  case List.head list of
    Nothing ->
      "0"
    Just val ->
      val

isEven : Int -> Bool
isEven num =
  num % 2 == 0

output : List String -> String
output args =
  getFirstArg args
  |> String.toInt
  |> Result.withDefault 0
  |> isEven
  |> toString
  
{-- run-elm IsEven.elm 23 --}