This is basically exactly how I understand functor/applicative/monad. I wonder how well it explains to someone whose not as familiar.
Where typeclass links to this other massive tutorial and then my eyes started to glaze over.
(Side note, this is probably the 50th or so Monad tutorial I've read and I still don't understand them. For context, I've been programming professionally for nearly 20 years now. My only conclusion at this point is either Monads aren't actually that important, or I actually do understand some useful subset of what Monads are and I just don't know it, and I just never had a need to use them "fully".)
Edited to add: I think my problem with Monad tutorials is that they all tend to explain the concepts using Haskell, and I can't read Haskell. It syntax is utterly impenetrable to me and I have no idea what any of the silly symbols mean. And any tutorial that tries to teach Monads using other languages ultimately feels like it's teaching me something I don't need to know... (how to do side effects in a pure functional language, when I don't code in pure functional languages and likely never will.)
As far as functors this could be rephrased more comprehensibly to those unfamiliar with Haskell as "What is a Functor, really? Functor is an interface here are some definitions:"
(typescript)
interface ArrayFunctor<A, B> {
map: (f: ((a: A) -> B), arr: Array<A>) -> Array<B>
}
interface PromiseFunctor<A, B> {
map: (f: ((a: A) -> B), arr: Promise<A>) -> Promise<B>
}
interface ObservableFunctor<A, B> {
map: (f: ((a: A) -> B), arr: Observable<A>) -> Observable<B>
}
interface Functor<F, A, B> {
map: (f: ((a: A) -> B), arr: F<A>) -> F<B>
}
> I actually do understand some useful subset of what Monads are and I just don't know it
This is certainly the case if you have ever used flatMap on an array or chained Promises (or other async structures like futures in other langs).