a699fb00 ​

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