Functors and Monads for People Who Have Read Too Many "Tutorials" (2021)

TBH, it took way too long to explain exactly what a "functor" is, and I find it pretty confusing.

In the section trying to finally define it, it starts off with "Functor is an interface...", and then ends the paragraph with "In Haskell's case, Functor, which is implemented by providing an fmap implementation. For the above examples, that function will:..."

So is it an interface or a function? Is it one and the same in Haskell? I am utterly confused.

If the goal was to explain anything simply, this article fails spectacularly for me.

Applicative is n-ary lifting, Functor is a special unary case of Applicative:

    liftA0 :: Applicative f => (a)                -> (f a)
    liftF1 ::     Functor f => (a -> b)           -> (f a -> f b)
    liftA2 :: Applicative f => (a -> b -> c)      -> (f a -> f b -> f c)
    liftA3 :: Applicative f => (a -> b -> c -> d) -> (f a -> f b -> f c -> f d)
    .. where
  liftA0 = pure
  liftF1 = fmap