typelead/eta

A dialect of Haskell on the JVM

Javier Neira

@jneira

Well the development rate is quite slow but we are acepting prs and try to help with issues

Mika Tammi

@mikatammi

I tried to add cassava (which depends on bytestring and bytestring-builder), as a dependency to Android app gradle project, but I get:

Execution failed for task ':app:checkDebugDuplicateClasses'.
> 1 exception was raised by workers:
  java.io.FileNotFoundException

From the scan I see the missing file is /home/username/.gradle/caches/etlas/eta-0865/bytestring-builder/0.0.0-inplace/bytestring-builder-0.0.0-inplace.jar (Is a directory)

I get the same error if I just try to depend on bytestring or bytestring-builder.

I guess the reason might be related to what is said on page of bytestring-builder: "Note that this package detects which version of bytestring you are compiling against, and if you are compiling against bytestring-0.10.4 or later, will be an empty package". So there really isn't any file. However, I don't get any errors if I just use etlas to build an application that has cassava as a dependency.

Nguyễn Anh Khoa

@nganhkhoa

Hey, just wondering, I notice that eta is developed with the idea that Java integrated into Haskell. Can you show me how can we intergrate Haskell into Java?
For example a library in Haskell and Java Main import and use.
Android application works this way, and by the current eta design (compileJava first then compileEta) and classpath is not included in the compile java too??

Alberto

@agocorona

@nganhkhoa For an android application in eta, see this: https://github.com/Jyothsnasrinivas/eta-android-2048

Nguyễn Anh Khoa

@nganhkhoa

@agocorona Well, I'm the one doing the fix for eta gradle to work with new android studio version and gradle version 5.0+. That project is no longer built with the current android studio and gradle 4.8+;5.0+.
I was just trying to figure out the class path injection when build a java project using eta as a library, the .jar file of eta doesn't linked to the build so an error emit saying there is no stg on eta.runtime (eta.runtime.stg.Closure error).

ShottyMonster

@ShottyMonster

hello

I am learning Haskell in my spare time, but have been using Java for several years and Kotlin for coming on 3 years. Interested in language design and compilers/transpilers, but yet to come up with novel syntax and write a parser/lexer etc. Would like to contribute if possible? Github: https://github.com/ThomasCookDeveloperInfo and https://github.com/ShottyMonster

Alberto

@agocorona

@nganhkhoa Ok! then you know it much better than me :smile:

Jeffrey Phillips Freeman

@freemo

Hi guys... quick question. I recently discovered ETA and wanted to start using it for my new "big" project.. but I got scared when Is aw it has been 6 months since even a commit. For a project as core as this (a language itself) this scares me a bit. Can someone help reassure me

Javier Neira

@jneira

@freemo Tbh the development is somewhat stalled, that said afaik there is no serious bugs and the released versions are pretty stable

Jeffrey Phillips Freeman

@freemo

@jneira my concern is that if it remains stalled it may go out of existance. The project i want to do would be a vital component in a larger java project. So that might be a real concern for me.

Javier Neira

@jneira

However to use last versions of haskell packages usually needs some work, cause they need to be patched

Jeffrey Phillips Freeman

@freemo

@jneira that might be a problem... shame i really wanted to find a reason to use haskell in a real project for a change.. might need to just use java or if i want something different maybe jython..

Javier Neira

@jneira

I dont think it will disappear though, @rahulmutt (main maintainer) and myself continue keeping a eye on it

But i understand your concerns

Jeffrey Phillips Freeman

@freemo

@jneira well thats good.. it is a bit concerning though that it isnt compatible with the newer versions of haskell .. i dunno i need to think about it, it might be ok actually since compatibility with java is more of a concern than haskell on this project

@jneira question.. is it doable to write code that compiles on both ETA and on standard haskell (GHC)?

Javier Neira

@jneira

Yeah, the unique caveat is eta supports fully ghc-7.10.3 and some features of ghc > 8.*, So you have to avoid the newest ghc/haskell ones to have code compilable with both eta and last ghc versions

the core of the haskell language is supported by eta

Jeffrey Phillips Freeman

@freemo

@jneira hmm might be doable then.. its a hard decision for me to make. I want to use haskell for the fun of it, I dont have a good reason beyond that. So the risks are a bit tougher to swallow

I'm tempted to just bite the bullet and give it a go

Javier Neira

@jneira

Sounds good, dont hesitate in posting any question here or in the github issue tracker

Jeffrey Phillips Freeman

@freemo

I will thank you

Jeffrey Phillips Freeman

@freemo

Does ETA fully support all java features... in particular can I write generic interfaces on the ETA side to be seen by the java side?

Javier Neira

@jneira

No specifically interfaces: you can export static methods or instance methods, with generics type parameters public <A> A static myMethod(A my param)

see https://eta-lang.org/docs/user-guides/eta-user-guide/java-interop/java-interop-basics#exporting-eta-methods

Jeffrey Phillips Freeman

@freemo

darn, if i cant produce interfaces I wont be able to use ETA for my project, since the purpose is to write a library intended for Java consumption and you cant do that (Sanely) without interfaces and generics :( Hopefully ill get a chance to try ETA another time.

Thans for your help though

Javier Neira

@jneira

mmm you can include java files in the eta project with the interfaces and use it for the default implementation(s) with haskell code, using exisiting packages

i did something alike to make a port between the dhall prog lang, written in haskell and java client code

Jeffrey Phillips Freeman

@freemo

Can I have *.java directly in an eta project? I thought java files would have to be in a seperate jar?

Javier Neira

@jneira

yeah, you can: see https://github.com/eta-lang/dhall-eta

Jeffrey Phillips Freeman

@freemo

ahhh ok yea that might be doable then, thanks ill check it out

Javier Neira

@jneira

that was my more elaborated lib using eta with the goal of being used from java client code

you can add the java files in the .cabal config file: https://github.com/eta-lang/dhall-eta/blob/master/dhall-eta.cabal#L88

But you can use gradle too: https://github.com/eta-lang/dhall-eta/blob/master/build.gradle

Jeffrey Phillips Freeman

@freemo

awesome! thanks

Sam Grönblom

@sgronblo

Is eta still alive?

Javier Neira

@jneira

Well, it is not dead 😜

Sam Grönblom

@sgronblo

https://github.com/typelead/eta "Latest commit Jul 16, 2019" Failing its tests even.

Javier Neira

@jneira

No bugs introduced since that date! 😛

Seriously, the released version is relatively stable, but the development is not active right now

So probably anybody using them will have to work on the tool itself

Sam Grönblom

@sgronblo

So what happened

Javier Neira

@jneira

Citing @rahulmutt (project owner):

"Hey guys, just wanted to announce that I’ve joined Symbiont as a full-time engineer. Things will move as usual, just a lot more slowly since I’ll be working at my leisure. For anyone looking to contribute, feel free to reach out as we could really use the help to speed things up a bit."

Sam Grönblom

@sgronblo

Thanks. That to me sounds like the end of Eta though.

Javier Neira

@jneira

Well, take a look at ghcjs, it is not very active (i have a pr to add support for windows for one year)

But i think having a haskell compiler to jvm bytecode has still sense, so i hope some day it can be reactivated in some way

Sam Grönblom

@sgronblo

Yeah I always was interested in this project. Even though I work in TypeScript and Node mostly. But I understand that Rahul has to support himself.

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