I've been learning about functional programming and have come across Monads, Functors and Applicatives.
From my understanding the following definitions apply:
a) ( A=>B ) => C[A] => C | Functor
b) ( A=>C ) => C[A] => C | Monad
c) ( C[A=>B] ) => C[A] => C | Applicative
(reference: <a href="https://thedet.wordpress.com/2012/04/28/functors-monads-applicatives-can-be-so-simple/" rel="noreferrer">https://thedet.wordpress.com/2012/04/28/functors-monads-applicatives-can-be-so-simple/</a>)
Furthermore, I understand a Monad is a special case of a Functor. As in, it applies a function <strong>that returns a wrapped value</strong> to a wrapped value and returns a wrapped value.
When we use
, we are passing the Promise(i.e. C[A]) a function which normally has signature
and return another Promise (i.e. C). So my thinking was that a Promise would only be a Functor and not a Monad as
returns B and not C.
However, googling I found out that a Promise is not only a Functor, but also a Monad. I wonder why, as
does not return a wrapped value C but just B. What am I missing?
From my understanding the following definitions apply:
a) ( A=>B ) => C[A] => C | Functor
b) ( A=>C ) => C[A] => C | Monad
c) ( C[A=>B] ) => C[A] => C | Applicative
(reference: <a href="https://thedet.wordpress.com/2012/04/28/functors-monads-applicatives-can-be-so-simple/" rel="noreferrer">https://thedet.wordpress.com/2012/04/28/functors-monads-applicatives-can-be-so-simple/</a>)
Furthermore, I understand a Monad is a special case of a Functor. As in, it applies a function <strong>that returns a wrapped value</strong> to a wrapped value and returns a wrapped value.
When we use
Code:
Promise.then(func)
Code:
A => B
Code:
funcHowever, googling I found out that a Promise is not only a Functor, but also a Monad. I wonder why, as
Code:
func