Possibly create a ChoiceT Monad Transformer

[Tombert]

Description

While I do see a ResultT transformer, several .NET libraries still use the (admittedly outdated) Choice type (e.g. Async.Catch). The Choice type is incompatible with the Result type.

Repro steps

N/A

Expected behavior

N/A

Actual behavior

N/A

Known workarounds

I suppose I could create a function called choiceToResult like this

let choiceToResult myThingy =
    match myThingy with
    | Choice1Of2 x -> Ok x
    | Choice2Of2 ex -> Error ex

However, this is a bit clunky since I'd have to pipe every Choice result into this function.

[wallymathieu]

There is this existing issue #52

[gusty]

Creating a ChoiceT may seem as easy as to copy-paste ResultT and replace Result with Choice but there are other implications: ResultT works with our MonadError abstraction, which by looking at the code should also work in theory with Choice.

We can test this approach by trying to re-write some sample code with ChoiceT

Otherwise it should be straight-forward to create an Async.Catch version that creates a Result instead of a Choice, we can call it Async.CatchToResult.

[wallymathieu]

Sounds like a nice thing for a pull request 😉 @Tombert

[wallymathieu]

I will start to look into making a PR for it @Tombert . We can pair on it if you want.