:: (a -> b) -> [a] -> [b] is:exact

`fmap` takes a function of type `a -> b`, and turns it into a function of type `f a -> f a`, where `f` is the type which is an instance of `Functor`. For example, `map` is an `fmap` that only works on lists. It takes a function `a -> b` and a `[a]`, and returns a `[b]`.
Synonym for `fmap`.
Map a function over a functor. Given a value `as` and a function `f`, `as <&> f` is `f <$> as`. That is, `<&>` is like `<$>` but the arguments are in reverse order.