Haskell: How to convert type “[[Int]] -> [(Int, Int, Int)]” to something of type “[[Int]] -> [[Int, Int, Int]]”

Question

I construct a function that returns lists of three elements, that is:

three [[5, 2, 3, 3], [8, 2, 2, 8], [9, 5, 5, 12], [12, 2, 33, 9]]

retur