Elm - select a random item from a list on every button click

select-random-on-click.elm

import Html exposing (..)
import Html.Events exposing (..)
import Signal
import Time
import Random
import Array

buttonMailbox =
  Signal.mailbox ()

buttonClicks : Signal Int
buttonClicks =
  Time.timestamp buttonMailbox.signal
    |> Signal.map fst
    |> Signal.map round

values : List String
values = ["foo","bar","qux","fux","tux"]

view time =
  let 
    seed = Random.initialSeed time
    lastItem = List.length values - 1
    generator = Random.int 0 lastItem
    randomIndex = fst (Random.generate generator seed)
    getValue item =
      case item of
        Just i
          -> i
        Nothing
          -> "error"
    value = values
      |> Array.fromList
      |> Array.get randomIndex
      |> getValue
  in
    div [] [
      text (toString values),
      div [] [text (toString randomIndex ++ " / " ++ toString lastItem)],
      div [] [text value],
      button [on "click" targetValue (\_ -> Signal.message buttonMailbox.address ()) ] [text "Surprise!"]
    ]

main =
  Signal.map view buttonClicks