WIP Re-add support for Scala 2.13

[denisgarci]

This is a first attempt at #732.
A few dependencies haven't yet been published:

• cats [WIP] move to Scala 2.13.0-RC1 (drop -M5) typelevel/cats#2783
• akka Upgrade to Scala 2.13.0-RC1 akka/akka#26691

Also I get the following error when running coreJVM/test:

[error] /Users/denisgarcia/dev/github/scalaz-zio/core/jvm/src/test/scala/scalaz/zio/RTSSpec.scala:1082:25: object interruptible is not a member of package scalaz.zio.blocking
[error]       fiber <- blocking.interruptible { start.set(()); Thread.sleep(Long.MaxValue) }.ensuring(done.set(true)).fork
[error]                         ^
[error] /Users/denisgarcia/dev/github/scalaz-zio/core/jvm/src/test/scala/scalaz/zio/RTSSpec.scala:1068:16: object blockingExecutor is not a member of package scalaz.zio.blocking
[error]       blocking.blockingExecutor.map(_.metrics.get.workersCount)
[error]                ^
[error] /Users/denisgarcia/dev/github/scalaz-zio/core/jvm/src/test/scala/scalaz/zio/RTSSpec.scala:1071:28: object blocking is not a member of package scalaz.zio.blocking
[error] did you mean Blocking?
[error]       thread1  <- blocking.blocking(IO.effectTotal(Thread.currentThread()))
[error]                            ^
[error] three errors found

I think it has to do with package object but I'm not sure how to fix it.

[jdegoes]

@denisgarci Cats would hold up publishing for cats-interop. The other ones should work. Is it possible to publish 2.13 for everything but cats-interop?

I can help fix that error.

[denisgarci]

@jdegoes Thanks for the feedback. I managed to make coreJVM test pass on my local branch!
To fix the blocking package object issue I removed the different specific 2.11 and 2.12 implementation and used the 2.11 package object (no inheritance) for all 3 versions.
Not sure if that's the best way to do it. Package object inheritance will be deprecated in 2.14 scala/scala#7857.
One of the problem I'm facing is that there are a lot of deprecation in scala.collection that makes some changes not backward compatible. What's the recommended approach? Copy the code in different 2.11_2.12 / 2.13 folder or maybe create a small collection utility wrapper?

[jdegoes]

@denisgarci

To fix the blocking package object issue I removed the different specific 2.11 and 2.12 implementation and used the 2.11 package object (no inheritance) for all 3 versions.

Arg. Not super happy about that. What if you change package object to just object? Does that make the errors go away?

Copy the code in different 2.11_2.12 / 2.13 folder or maybe create a small collection utility wrapper?

A small collection utility wrapper would work best! Then the core code will be common.

Also, it's possible there are already enough overlapping methods we can get it compiling without a common utility wrapper.

[jdegoes]

@denisgarci If you run fmt, it will fix the linting error. Then I'd add 2.13 to the Travis file to get it building on Travis too.

[denisgarci]

So I've pushed all the 2.13 only changes with comments. I couldn't make the blocking package object work. It currently lives in 2.12/ folder. Should I rename it to 2.12+/?

[jdegoes]

@denisgarci Can you tell me the error? I'd be happy to help you with that.

I'd love to get this pull request merged in for RC5 (coming this week).

[denisgarci]

I don't have access to a computer this weekend. I'll be able to work on it next week though.
My biggest problem right is method that have been deprecated for a a specific Scala version.
For example . lines (2.11 & 2.12) vs . linesIterator (2.12+ only). Or .enqueue vs .enqueueAll.

[jdegoes]

@denisgarci Please let me know if you need any help with this!

[denisgarci]

Closing for now see #732 (comment)