indexed_colors.elm

import Dict

indexed: [a] -> Dict.Dict Int a
indexed list = Dict.fromList (zip [0..(length list)] list)

type Palette = Dict.Dict Int Color

makePalette: [Color] -> Palette
makePalette colors = indexed colors

palette = makePalette [red, orange, yellow, green, blue, purple]

colorAt: Palette -> Int -> Color
colorAt p i = case Dict.lookup i p of
      Just c -> c
      Nothing -> black

cellAt: Int -> Int -> Form
cellAt x i = moveX (toFloat (5 + x * 10)) (filled (colorAt palette i) (rect 10 10))

rowAt: Int -> [Int] -> Form
rowAt y pixels = moveY (toFloat (-5 - y * 10)) (group (zipWith cellAt [0..(length pixels)] pixels))

grid: [[Int]] -> Element
grid pixels = 
  let width = 10 * (length (head pixels))
      height = 10 * (length pixels)
  in
    collage width height [(move (toFloat(-width)/2,toFloat(height)/2) (group (zipWith rowAt [0..(length pixels)] pixels)))]

main: Element
main = grid [[0,1,2,3,4,5], [1,2,3,4,5,6], [2,3,4,5,6,7]]