String Calculator Kata in Elm

main.elm

import Graphics.Element (..)
import Graphics.Input.Field (Content, Selection, Direction(..))
import Graphics.Input.Field as Field
import Signal
import Time
import String
import List
import Result
import Text (plainText)
import Debug


content : Signal.Channel Field.Content
content =
  Signal.channel Field.noContent

convert result =
  case String.toFloat result of
    Result.Ok n -> n
    Result.Err s -> 0

calculate : String -> Float
calculate s =
  List.foldl (+) 0 <| List.map convert <| spaceSplit s

spaceSplit =
  String.split " "

sumString =
  toString << calculate << (.string)

main : Signal Element
main =
  Signal.map (\s -> (scene s) <| sumString s) <| Signal.subscribe content

scene : Field.Content -> String -> Element
scene fieldContent result =
   flow down
   [ Field.field Field.defaultStyle (Signal.send content) "Type here!" fieldContent
   , plainText result
   ]