4. Write the type of each of the following terms in the simply-typed lambda calculus. Again, you do not need to write proof trees, but it might help. Make sure to write parentheses when needed: the -> is right-associative by default, so that int int int means int (int int) and not (int int) int. xx : int. Xy : int. x + y Xy : int. Af : int -> int. f y ( : int. Af : int int, f y) (4) (Af : int int. Ay : int, f (f y)) ( : int. x + 1) 4. Write the type of each of the following terms in the simply-typed lambda calculus. Again, you do not need to write proof trees, but it might help. Make sure to write parentheses when needed: the -> is right-associative by default, so that int int int means int (int int) and not (int int) int. xx : int. Xy : int. x + y Xy : int. Af : int -> int. f y ( : int. Af : int int, f y) (4) (Af : int int. Ay : int, f (f y)) ( : int. x + 1)