either VS recursion-schemes

Restricting what can go into a Result in the error variant is quite restrictive. It's often very convenient to use Result as a sort of "this or that" type without any connotations about errors, particularly as an internal convenience. Arguably one might want to use either instead, but it's a lot of ceremony to bring that in for simple use cases.

P.S. you can use either to make it work on stable rustc

The European Union does not have as large a software industry as the USA so there would be a less strong argument of government/corporate competition. It could take the form of government grants depending on the size. My rationale is that governments benefit from the general prosperity of open source more so than solo authors or small companies.

I am restricting the scope to simple and small libraries where investment is more clearly beneficial unlike Tensorflow as that is large and complex.

Here is an extreme example, the 'either' crate is a 'rayon' dependency and many others. Paradoxically a project of this size likely does not need funding but it is really important.

https://github.com/bluss/either

Reasonably proud of my part 2 solution, although would like to try using a recursion scheme rather than unstructured recursion:

Yeah, that project is pretty much at the bottom of my list, unfortunately. My top projects these days are mgmt, klister, recursion-schemes, and hint... And that's already too much!

In a programming context, recursion schemes can be used to write recursive (or corecursive) functions, by automating/abstracting away the common boilerplate part of actually doing the recursion. They take the form of polymorphic higher-order functions, which can be imported from a library like this classic one.

Maybe I didn't link the best post. It is unfortunately the only one I know that uses Rust. If you are able to read Haskell, the documentation for the recursion-schemes package might be a better resource?

Writing something as a type of fold over an infinite sequence is nicer than using recursion directly in my opinion. See: https://hackage.haskell.org/package/recursion-schemes

Consider recursion schemes! It let's you separate the logic of how your recursion is structured on your data, and the logic of what you're doing on each recursion stage. So e.g. you can write the core logic of a recursive linked list summation as just fun x accum -> x + accum, and then you just find the appropriate recursion scheme to pipe the list values into x and handle recursing to build accum (a catamorphism in this case)

It's a pretty complicated bug, documented in details at https://github.com/recursion-schemes/recursion-schemes/issues/50

It’s also trivial and easy in Haskell — you just need an instance of `Foldable` or `Traversable` on your collection, and then you can fold or traverse it in a configurable way. Or for recursive structures, use https://hackage.haskell.org/package/recursion-schemes. Or even just pass a traversal function as an argument for maximum flexibility.

https://hackage.haskell.org/package/recursion-schemes is the "normal" library for this type of generalized folding. It even contains Base instances for Maybe and Either.

I've been working on a system which uses recursion-schemes to annotate a recursive type. The annotated tree itself is pretty simple; at each level, we pair the annotation with the base functor, or