Update of this code: http://codereview.stackexchange.com/questions/29823/can-this-be-written-more-concise-and-aligned-with-the-functional-reactive-progra

RandomFruit.elm

import Random
import Mouse
import Graphics.Collage exposing (toForm, move, collage)
import Graphics.Element exposing (show)
import List exposing (..)
import Time

type Fruit = Apple | Orange | Banana | Melon | Guava

-- For module global declarations, it is often helpful to
-- explicitly annotate the types.
fruits : List Fruit
fruits = [Apple, Orange, Banana, Melon, Guava]

-- especially for functions :)
fruit : Int -> Fruit
fruit n = Maybe.withDefault Apple <| head <| drop n fruits

type alias RandModel = (Int, Random.Seed)

rr2 : RandModel -> RandModel
rr2 m = Random.generate
  (Random.int 0 (length fruits - 1))
  (snd m)

rand : Signal Int
rand =  Signal.map fst <| Signal.foldp (always rr2) (0, Random.initialSeed 0) Mouse.clicks

fruitText : Signal Graphics.Collage.Form
fruitText =  Signal.map (toForm << show << fruit ) rand

time = Signal.map
  (Time.inSeconds << fst)
  (Time.timestamp (Time.fps 40))

scene dy form = Graphics.Collage.collage 300 300 [move (0, 100 * cos dy) form]

main = Signal.map2 scene time fruitText