a740d043 ​

input = fill #0 (fill #1 blue) |> fold (λr. rect ((r.2, #2, r.3, #3), r.1)) #4 |> rect ((#5, #6, #7, 3h), #8)
output = #9
(VInt, HInt, HInt, HInt, UList (Color, VInt, VInt), VInt, HInt, VInt, Color, OList OList Color)
(5v, 7h, 4h, 4h, {(red, 4v, 4v), (green, 3v, 3v)}, 2v, 2h, 3v, red, [[red, red, black], [red, red, green], [black, black, red]])
(7v, 7h, 5h, 5h, {(red, 2v, 3v)}, 2v, 3h, 3v, green, [[green, black, red], [green, black, red]])
(7v, 6h, 2h, 3h, {(fuschia, 5v, 5v)}, 3v, 2h, 4v, grey, [[grey, grey], [grey, grey], [fuschia, fuschia]])
(6v, 6h, 4h, 4h, {(green, 4v, 4v), (red, 3v, 3v)}, 4v, 3h, 4v, red, ?)