data LengthMatch : List a -> List b -> TypeNilMatch : LengthMatch [] []ConsMatch : LengthMatch xs ys -> LengthMatch (x :: xs) (y :: ys)checkLengthMatch : (xs : List a) -> (ys : List b) -> Maybe (LengthMatch xs ys)lengthsMatch : LengthMatch xs ys -> length xs = length ys