575b1a71 ​

input = fill 10v (fill 10h grey) |> fold (λr. rect (r, black)) #0
output = fill 10v (fill 10h grey) |> fold (λr. rect ((r.2, r.3, r.4, r.3), r.1)) #1
(UList (VInt, HInt, VInt, HInt), UList (Color, VInt, HInt, VInt))
({(5v, 5h, 7v, 5h), (5v, 5h, 5v, 6h), (4v, 6h, 5v, 6h), (8v, 9h, 10v, 9h), (1v, 6h, 1v, 6h), (9v, 5h, 9v, 6h), (9v, 2h, 9v, 2h), (6v, 2h, 7v, 2h), (4v, 2h, 4v, 2h)}, {(yellow, 8v, 9h, 10v), (green, 1v, 6h, 1v), (green, 9v, 6h, 9v), (red, 9v, 5h, 9v), (blue, 9v, 2h, 9v), (blue, 6v, 2h, 7v), (red, 5v, 5h, 7v), (green, 4v, 6h, 5v), (blue, 4v, 2h, 4v)})
({(10v, 5h, 10v, 5h), (1v, 8h, 1v, 8h), (1v, 1h, 1v, 1h), (9v, 9h, 9v, 9h), (8v, 5h, 8v, 5h), (5v, 5h, 5v, 5h), (4v, 8h, 4v, 8h), (3v, 5h, 3v, 5h)}, {(red, 10v, 5h, 10v), (green, 1v, 8h, 1v), (blue, 1v, 1h, 1v), (yellow, 9v, 9h, 9v), (red, 8v, 5h, 8v), (red, 5v, 5h, 5v), (green, 4v, 8h, 4v), (red, 3v, 5h, 3v)})
({(6v, 9h, 6v, 10h), (4v, 10h, 6v, 10h), (9v, 10h, 9v, 10h), (1v, 6h, 1v, 7h), (8v, 7h, 8v, 7h)}, {(yellow, 9v, 10h, 9v), (yellow, 4v, 10h, 6v), (red, 1v, 7h, 1v), (blue, 1v, 6h, 1v), (red, 8v, 7h, 8v), (green, 6v, 9h, 6v)})
({(10v, 6h, 10v, 6h), (10v, 1h, 10v, 1h), (8v, 1h, 8v, 1h), (4v, 1h, 4v, 1h), (1v, 4h, 1v, 4h), (6v, 3h, 7v, 3h), (5v, 6h, 5v, 6h)}, ?)