c0f76784 ​

input = fill 12v (fill 12h black) |> fold (λr. rect ((r.1 - 1, r.2 - 1, r.3 + 1, r.4 + 1), grey)) #0 |> fold (λr. rect (r, black)) #0
output = fill 12v (fill 12h black) |> fold (λr. rect ((r.1, #1, r.2, r.3), grey)) #2 |> fold (λr. rect ((r.1, r.2, #3, r.3), grey)) #4 |> fold (λr. rect ((r.2, #5, r.3, r.4), r.1)) #6 |> fold (λr. rect ((r.2, r.3, #7, r.4), r.1)) #8
(UList (VInt, HInt, VInt, HInt), HInt, UList (VInt, VInt, HInt), VInt, UList (VInt, HInt, HInt), HInt, UList (Color, VInt, VInt, HInt), VInt, UList (Color, VInt, HInt, HInt))
({(2v, 9h, 4v, 11h), (8v, 8h, 9v, 9h), (4v, 4h, 4v, 4h)}, 7h, {(7v, 10v, 10h)}, 5v, {(1v, 8h, 12h), (3v, 3h, 5h)}, 8h, {(orange, 8v, 9v, 9h)}, 4v, {(teal, 2v, 9h, 11h), (fuschia, 4v, 4h, 4h)})
({(2v, 3h, 3v, 4h), (9v, 3h, 9v, 3h), (6v, 8h, 8v, 10h)}, 2h, {(1v, 4v, 5h), (8v, 10v, 4h)}, 9v, {(5v, 7h, 11h)}, 3h, {(orange, 2v, 3v, 4h), (fuschia, 9v, 9v, 3h)}, 8v, {(teal, 6v, 8h, 10h)})
({(9v, 6h, 10v, 7h), (3v, 3h, 5v, 5h)}, 5h, {(8v, 11v, 8h)}, 6v, {(2v, 2h, 6h)}, 6h, {(orange, 9v, 10v, 7h)}, 5v, {(teal, 3v, 3h, 5h)})
({(10v, 6h, 11v, 7h), (6v, 10h, 6v, 10h), (3v, 3h, 5v, 5h)}, ?, ?, ?, ?, ?, ?, ?, ?)