Random walk in Elm

randomWalk.elm

import Random

(w,h) = (600, 400)
initialPosition = (0, 0)

intToDir d n =
    if d < 0.5
    then n
    else -n

step : Signal Float -> Signal (Float, Float)
step s =
    let dx = Random.float s
        dy = Random.float s
        dirX = Random.float s
        dirY = Random.float s
    in lift2 (,) (lift2 intToDir dirX dx) (lift2 intToDir dirY dy)

translate (x, y) (dx, dy) = (x+dx, y+dy)

walk = foldp (\delta acc -> (translate (head acc) delta) :: acc)
       [initialPosition]
       (step (fps 100))

draw p = collage w h
         [ traced (solid lightBlue) <| path p ]

main = lift draw walk