[adriaanm]

We share your concern. As I said in my comment above -- the Scala and Dotty teams actively work together (we have our roots in the same research group at EPFL) to make sure Scala 2.x evolves towards Dotty and Dotty evolves towards Scala 2.x. Scala 2.12 and 2.13 will have language flags that unlock features being incubated in Dotty that we can already implement, and the Dotty compiler already has a Scala 2 compatibility mode.

We take continuity very seriously. No one wants a Python 3-style transition. In addition to the desire to avoid this, we also have a type system and a community build (think Google Blaze for Scala) that builds > 1MLoC OSS Scala code.

[nrinaudo]

Thanks for taking the time to share this. I was aware of the community build - I believe it was discussed in some depths on Scalawags a while ago? - and find it to be an amazing initiative. Can't think of a better way to minimise the issues that Dotty might cause, and I'm in awe of the amount of work it must represent.

What I fear in that moment down the line where one feature goes over the arbitrary threshold you set yourself for community breakage, but is just too great to pass up on. Since the threshold is arbitrary anyway, it's fine to adjust it a bit... and a bit more later...

Not saying it will happen, and it would be dishonest of me not to say that I don't think you could possibly do more than you're already doing to prevent this kind of issue.