Function type in case pattern shouldn't be allowed

[hhefesto]

This compiles and runs, and shouldn't.

main = \input -> case input of
                   0 -> ("enter input", 1)
                   (a, b) -> let myConst = \x -> x
                             in case myConst of
                                  (a,(0,(0,0))) -> ("length 0", 0)
                                  (a,(0,(1,0))) -> (a, 0)
                                  ["hhefesto0", ([x, 1, "hhefesto2"], 0)] -> (x, 1)
                                  x             -> ("default case", 0)