FYI: Second day into Haskell

MRE (what the function does, does not matter):

foo :: Int -> Int -> Int
foo x y
        | x == y = x + y
        | x < y = x
        | x > y = y

This is what I’ve gathered about the -> operator(?) so far:

1. It is right-associative
2. It is used in function type declaration to denote the type of function parameters as well as its return type

Now take a look at the following function type declaration:
foo :: Int -> Int
This declares(what is the appropriate word?) a function called foo that takes an Int and returns an Int.

However, the declaration: foo :: Int -> Int -> Int declares(?) that foo takes 2 Ints and returns an Int when it is the same as saying foo :: Int -> (Int -> Int) which is a function that takes an Int and returns a function that takes an Int and returns an Int.

How does this make sense? Should it not be something on the lines of Int,Int -> Int?

PS: The book I’m using: Thinking Functionally with Haskell by Richard Bird.