b60334d2 ​

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