f8ff0b80 ​

let ps: OList (Color, OList (Int, Int))

let input = fill 12 (fill 12 black)
  |> fold (λ(c, ps). fold (λp. point p c) ps) ps

let output = ps
  |> sort (λ(c, ps). -len ps)
  |> map (λ(c, ps). [c])