" Free모나드 는 공짜라서 Free 모나드가 아닙니다. "
https://lionhairdino.github.io/posts/2024-12-15-freeMonadV2.html
하스켈 을 공부하고 있고, 모나드 를 알고 있는 분들 중, Free 모나드가 손에 잘 잡히지 않는 분들이 볼만한 상상 글입니다.(쉽게 쓰려고 수학을 뺀 게 아니라, 몰라서 수학적인 건 없습니다.)(SNS를 시작한지 얼마 안되어, 여기 저기 모두 올려 봅니다. 중복 정보를 받으시는 분들은 이해 부탁 드립니다.)

#Free모나드 #FreeMonad #모나드 #Monad #하스켈

To my surprise, the idea I had last night is actually working just fine in #RustLang.

So, my #VisualNovel #SpareTimeProject is now probably going to use an #eDSL encoded as a #FreeMonad which is wrapped in a #StateMonadTransformer.

Now I just need to continue working on it. I haven't made much progress in the last 9 months...

Nicolas Rinaudo THE DEBATABLY FREE MONAD Scalar Conference 2024
https://www.youtube.com/watch?v=Yci07bMTcsM

#fp #scala #freemonad #programming

Yesterday I ported Haskell's State Monad Transformer to #RustLang. That should make tracking the game state in my #FreeMonad based embedded Domain Specific Language for scripting the story in my spare time #VisualNovel #GameDev project way easier.

Also, the currently released version of "higher" has the limitation that bindings in do-notation only work well with Copy types. The State Monad Transformer doesn't have this limitation and can store any state that is Clone.

@joenash The blog posts https://www.haskellforall.com/2012/07/purify-code-using-free-monads.html & https://www.haskellforall.com/2012/06/you-could-have-invented-free-monads.html by @GabriellaG439 about #FreeMonad|s seem related. They don't contain this claim verbatim, but a kinda lemma of it: «[…] we can always factor out impure parts from any code by using free monads. Free monads let you decompose any impure program into a pure representation of its behavior and a minimal impure interpreter[…]»

@donsbot

I've started some architecture work for my potential #VisualNovel spare time project. I must say I'm torn between using a #FreeMonad for storytelling, or going the usual #RustLang way of using a trait...

A Free Monad would decouple the storytelling from the user interaction completely, and its internal state would become trivial to manage.

A trait would allow to utilize Rust's borrow checker to ensure a situation's consistency. For instance one could tie a character's lifetime to the location.

On the topic of #FreeMonad in #RustLang: I found out that there is another package on crates.io, that was released a few weeks before my higher-free-macro macro:
https://crates.io/crates/algar

Unlike my code algar is using a generic type instead of a macro, what is possible because it has different Functor/Monad/... traits that use an associated type to specify the domain.

On the other hand, algar has limitations that higher-free-macro does not have. Its Monad can only bind with FnOnce, for instance.

I went ahead and published my small #FreeMonad crate for #RustLang officially today.

https://crates.io/crates/higher-free-macro

This crate employs a macro to create a Free Monad type for a user-supplied Functor. The Free Monad is implemented as a recursive data type with Box as indirection.

It uses the traits from the "higher" crate by @bodil to express what a Functor/Monad/etc. is.

Today I've added an example to my #FreeMonad in #RustLang project.
It is pretty bad code, but that's what happens if one intentionally makes bad decisions in order to highlight issues and potential workarounds...

For instance, I used a `Vec` where a 3-element array would have sufficed, making me write a ton more `clone()` calls than I ever wanted...

Still, I'm pretty happy how small the interpreter turned out, and how easy it was to focus on the actual game logic:
https://github.com/soulsource/higher-free-macro/tree/main/examples/text-adventure