Monads are monoids in the category of endofunctors

Re:Monads are monoids in the category of endofunctors by Littlebigo on Thursday September 09, 2021 @10:34PM (#28477148)

To add, I suspect that the Haskell type notation is not intuitive to people not familiar with it. For anyone wondering, (a -> b) -> f a -> f b means "A function taking a function from one type to another "(a -> b)" and a functor applied with one type "(f a)" and returns a functor applied with another type "(f b)".

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Re:Monads are monoids in the category of endofunctors by Twisol on Thursday September 09, 2021 @11:07PM (#28477352)

I do think familiarity plays a big role. I find the Haskell syntax much more pleasant than Java, even though I'm perfectly familiar with both.

The equivalent signature in Java (if we could abstract over type functions) would be:

    interface Functor<F<_>> {
      <A, B> Function<F<A>, F<B>> map(Function<A, B> f);
    }

You'll find very similar in Scala's `cats`, up to some currying and reordering. [0]

[0] https://typelevel.org/cats/typeclasses/functor.html

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Re:Monads are monoids in the category of endofunctors by Littlebigo on Thursday September 09, 2021 @11:15PM (#28477410)

I absolutely agree, I was just adding the explanation for anyone unfamiliar with the syntax.

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Re:Monads are monoids in the category of endofunctors by Twisol on Thursday September 09, 2021 @11:17PM (#28477432)

And I was building on yours :) I hope you didn't mind.

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