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This repo holds code that will be added to a future version of the Scala standard library.

We will publish this as a library, to make the additions usable immediately. But publishing hasn't happened yet. (The repo only just started, in October 2020.)


Why make a library for this? Because:

  • Scala 2.13 is expected to be final major release of Scala 2.
  • We cannot make additions to the standard library in the Scala 2.13.x series, because of our binary compatibility constraints.
  • To help users transition from Scala 2 to 3, Scala 2.13 and 3.0 will share the same standard library.

Therefore, additions to the library cannot happen until Scala 3.1 at the earliest.

But why publish the additions separately in the meantime? Because:

  • Users may find the additions useful now.
  • Having users start using the additions now will help shake out problems early.
  • Contributors will be more motivated to work on improvements if users can use them now.

What can be added?

Anything merged here will become part of the next Scala standard library.

Therefore, we will not merge anything here unless the Scala 2 and 3 teams agree on the addition. The bar for accepting additions remains very high.

Is it okay to open an issue and/or pull request regardless? Yes, definitely. Let's discuss your idea. Just be aware that the bar is high and contributions may be rejected unless there is a high degree of consensus and confidence that it really belongs in the standard library.

It's not required, but you may wish to bring your idea up on first to gauge reaction.

There are may be technical constraints on what can be added, since this a separate codebase from the actual standard library. So for example if you want to add a new method to an existing class, it must be added as an extension method. We are still discussing details on issue #4.

What if my contribution is rejected?

If your contribution is collections-themed, it could find a home at scala-collection-contrib, which has a much more liberal merge policy.

You might also consider publishing your code yourself in a separate library, of course.


The discussions that led to this repo being created are here:

The name was discussed here:


backwards-binary-compatible Scala standard library additions



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