Generalizing over Generics in Rust (Part 1) - AKA Higher Kinded Types in Rust Do you want to use Higher Kinded Types (HKT) in Rust? Are you tired of waiting for GAT? Well, this is the place to be.

Is it feasible to implement join, i.e. bind(id) in the most general fashion? The special case of Option: fn join<X>(mmx: Option<Option<X>>) -> Option<X> { OptionFamily.bind(mmx, |mx| mx) }

Yes, you can. I just chose what Haskell did, with no real reason. Thinking about it now, it would be less efficient to use join. For example, if you want a family over Vec, join would require you to have a Vec<Vec<_>>, which could be a lot of memory at once. Using bind can reduce the maximum memory …

Now I've ended up in something working. It turns out to be pretty straightforward: fn join<M, X>(m: M, mmx: This<M, This<M, X>>) -> This<M, X> where M: Monad<This<M, X>, X> { m.bind(mmx, |mx| mx) }

Generalizing over Generics in Rust (Part 1) - AKA Higher Kinded Types in Rust

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RustyYato February 16, 2021, 6:19pm 2

This was requested over on reddit by /u/CalligrapherMinute77

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Generalizing over Generics in Rust (Part 1) - AKA Higher Kinded Types in Rust

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