d364b489 ​

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