Yes, in Haskell the type [Integer] is not a monad. For a type to be an instance of the Monad type class, it must be of kind * -> * . As [Integer] is of kind * , it cannot possibly be an instance of Monad.
I didn't mean to suggest that [Integer] was of type Monad, I meant that when you write code in terms of the List monad, that code still works and is still valid and is still "monadic" even when the input to that code is a list of a non-polymorphic type.
I really don't follow what you're trying to say here. >>= has signature m a -> (a -> m b) -> m b, so clearly you are working with a concrete type m a. The point is that the concrete type isn't what instantiates the Monad type class, the constructor m is.
