Macros is Scalaz

[Jean-Rémi Desjardins]

Hi,

I noticed that there are no macros within scalaz right now (or am I wrong?).

Is there any chance whatsoever, that a contribution involving macros would be accepted within scalaz?

Cheers,

[Alois Cochard]

Hi Jean-Rémi,

You might have more feedback if you explain what you actually have in mind, I mean which problem do you want to solve using macros?

I'm of the one who prefer to avoid them as much as possible, but maybe you have a strong case for it?

Cheers

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[Jean-Rémi Desjardins]

Of course! I was trying to keep the question as simple as possible, but I would be delighted to talk about what I have been working on.

Over the holidays, I started prototyping the idea of an Idiom Bracket notation in Scala using macros. It turns out it is possible and I am hoping it will be useful.

Up until now, I took the path of least resistance and have been doing my work in a branch on my fork of Scalaz since Idiom Brackets are based on the notion of an Applicative Functor (which happens to be nicely defined in Scalaz).

I have thought about whether it could be included in Scalaz as syntactic sugar for Applicative. I think it's probably best if it lives in a separate repo but wanted to get some feedback on that.

[Brian McKenna]

There's been some prior art in this area:

https://github.com/aztek/scala-workflow

I would love for this to work in a similar way - as a separate artifact.

Part of the problem is that scalaz 7.1 supports Scala 2.9. I think the
plan is to kill that off in 7.2 and just support 2.10 and 2.11 but
macros changed a bit between those versions and are a pain to make
work across versions.

On 11 January 2015 at 14:43, Jean-Rémi Desjardins

[Tony Morris]

Slightly pedantic, but consider idiom brackets based on Apply (not Applicative). No need for pure.

[Jean-Rémi Desjardins]

@Brian McKenna Thanks for pointing me towards scala-workflow! That's awesome.

[Alois Cochard]

Great stuff!

This is -for me- a very good case for using macro/compiler-plugin, as this great tool by Erik: https://github.com/non/kind-projector it probably deserve to be in is own repo.

Once stabilized I can see it as being part of a scalaz module though.

Looking forward playing with your syntax!