Thanks a lot for the in-depth explanation! May I pick your brain a bit more on this topic?
1. Do you know what were the main arguments for and against using typeclasses vs modules for abstraction? It's interesting to read that traits wound up in the language against Graydon's preferences.
2. There's another commenter on this thread suggesting that 'Typeclasses are just OOP interfaces' who has gotten a bit downvoted. To me they seem kind of the same thing, yet at the same time there's this feeling that I'm overlooking something and typeclasses are likely 'so much more powerful'. I just can't figure out what that may be. So, are there any major differences between what interfaces are in OOP and what typeclasses/traits are?
The power of Haskell's type classes comes from two things:
* Implicit composition of instances: you can write `show [True, False]`, which will automatically/implicitly compose the `Show` instances of lists and booleans. With modules or interfaces, you'd have to build and use a "BoolListShow" manually.
* Higher-kinded types, to abstract over type constructors. This enables the use of abstractions like monads.
Rust only has the first of these two.
Scala uses OOP interfaces instead, but by augmenting them with both capabilities (implicit composition and higher-kinded types), it achieves the same expressiveness as Haskell.
1. Do you know what were the main arguments for and against using typeclasses vs modules for abstraction? It's interesting to read that traits wound up in the language against Graydon's preferences.
2. There's another commenter on this thread suggesting that 'Typeclasses are just OOP interfaces' who has gotten a bit downvoted. To me they seem kind of the same thing, yet at the same time there's this feeling that I'm overlooking something and typeclasses are likely 'so much more powerful'. I just can't figure out what that may be. So, are there any major differences between what interfaces are in OOP and what typeclasses/traits are?