Language-Ext 5.0 alpha-1

[louthy]

This release should only be consumed by those who are interested in the new features coming in the monster v5 release.

Just to give you an idea of the scale of this change:

• 193 commits
• 1,836 files changed
• 135,000 lines of code added (!)
• 415,000 lines of code deleted (!!)

It is a monster and should be treated with caution...

• It is not ready for production
• It is not feature complete
• The new features don't have unit tests yet and so are probably full of bugs
• I haven't yet dogfooded all the new functionality, so it may not seem as awesome as it will eventually become!

If you add it to a production project, you should only do so to see (potentially) how many breaking changes there are. I would not advise migrating a production code-base until I get close to the final release.

I am also not going to go into huge detail about the changes here, I will simply list them as headings. I will do a full set of release notes for the beta release. You can however follow the series of articles I am writing to help you all prep for v5 -- it goes (and will go) into much more detail about the features.

New Features

• Higher-kinded traits
  • K<F, A> - higher-kinds enabling interface
  • Includes:
    • Defintions (interfaces listed below)
    • Static modules (Functor.map, Alternative.or, StateM.get, ...)
    • Extension methods (.Map, .Or, Bind, etc.),
    • Extension methods that replace LanguageExt.Transformers (BindT, MapT, etc. ), now fully generic.
    • Trait implementations for all Language-Ext types (Option, Either<L>, etc.)
  • Functor<F>
  • Applicative<F>
  • Monad<M>
  • Foldable<F>
  • Traversable<T>
  • Alternative<F>
  • SemiAlternative<F>
  • Has<M, TRAIT>
  • Reads<M, OUTER_STATE, INNER_STATE>
  • Mutates<M, OUTER_STATE, INNER_STATE>
  • ReaderM<M, Env>
  • StateM<M, S>
  • WriterM<M, OUT>
  • MonadT<M, N> - Monad transformers
    • ReaderT<Env, M, A>
    • WriterT<Out, M, A>
    • StateT<S, M, A>
    • IdentityT<M, A>
    • EitherT<L, M, R>
    • ValidationT<F, M, S>
    • OptionT<M, A>
    • TryT<M, A>
    • IdentityT<M, A>
    • ResourceT<M, A>
• Free<F, A> - Free monads
• IO<A> - new IO monad that is the base for all IO
• Eff<RT, A> monad rewritten to use monad-transformers (StateT<RT, ResourceT<IO>, A>)
• Eff<RT, A> doesn't need HasCancel trait (or any trait)
• Transducers
• Pure / Fail monads
• Lifting
• Improved guards, when, unless
• Nullable annotations - still WIP, mostly complete on Core)
• Collection initialisers

Breaking changes

• netstandard2.0 no longer supported (.NET 8.0+ only)
• Seq1 made [Obsolete]
• 'Trait' types now use static interface methods
• The 'higher-kind' trait types have all been refactored
• The Semigroup<A> and Monoid<A> types have been refactored
• The static TypeClass class has been renamed Trait
• Apply extensions that use raw Func removed
• Manually written Sequence extension methods have been removed
• Manually written Traverse extension methods have been removed
• ToComparer doesn't exist on the Ord<A> trait any more
• Renamed LanguageExt.ClassInstances.Sum
• Guard<E> has become Guard<E, A>
• UnitsOfMeasaure namespace converted to a static class
• Either doesn't support IEnumerable<EitherData> any more
• Either 'bi' functions have their arguments flipped
• Nullable (struct) extensions removed
• Support for Tuple and KeyValuePair removed
• Types removed outright
  • Some<A>
  • OptionNone
  • EitherUnsafe<L, R>
  • EitherLeft<L>
  • EitherRight<L>
  • Validation<MFail, Fail, A>
  • Try<A>
  • TryOption<A>
  • TryAsync<A>
  • TryOptionAsync<A>
  • Result<A>
  • OptionalResult<A>
  • Async extensions for Option<A>
  • ExceptionMatch, ExceptionMatchAsync, ExceptionMatchOptionalAsync
• Libraries removed outright
  • LanguageExt.SysX
  • LanguageExt.CodeGen
  • LanguageExt.Transformers

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This discussion was created from the release Language-Ext 5.0 alpha-1.

[earnest]

@louthy thanks for updates. I haven't looked extensively at the v5 yet, so apologies if this has been answered, I am currently using TryAsync(()=>computeResult).ToEither. If this is removed, what is the alternative way, please? Would we have to use Eff/Aff? Any particular motivation in removing it?

[louthy]

It depends what you need (Aff is removed also btw).

• Eff<A> will do everything you need and will also do resource tracking (automatic clean up of use resources)
• TryT<IO, A> which uses the new monad transformers is isomorphic go TryAsync -- it is simpler and more lightweight than Eff but has fewer features.

Also, because this library is MIT licensed, you can just go and copy the original TryAsync code if you want to keep using it and maintain it for yourself. You have every right to just take it and do what you want with it! 👍

Some more info:

• Proposal from 6 months ago to de-Async the library
• 'EitherAsync is missing' issue raised with some context from me
• My blog with an intro to higher-kinds with language-ext v5

[WizMe-M]

Hi, @louthy!
I'm little late... sorry for that.

What's the point of removing these types? How does v5 extensions expect user to handle A | Exception and A | None | Exception cases?

• Types removed outright
  • ...
  • Result<A>
  • OptionalResult<A>

[louthy]

https://github.com/louthy/language-ext/wiki/Frequently-Asked-Questions#where-is-result