Implement SIP-42 - Support for binary integer literals

[Sporarum]

Implement, test and document SIP-42

(Implement is a strong word, I uncommented a single line)

[odersky]

Is it in the Scala 2 spec? If not we need a doc page for the change. As often docs are harder than code.

[som-snytt]

I had forgotten that I forward-ported the commented code with other fixes.

The old NthPortal PR was https://github.com/scala/scala/pull/8275/files which had only the syntax summary tweak. It has some more tests.

Nth's comment:

what I actually should have tested is 0b1 // Kenobi

That effort was in the six months leading up to the pandemic. My opinion is that it was unfortunate to put Scala 3 uptake in the path of Scala 2. That is, 0b syntax could have benignly coexisted. It would have blocked no one's migration and confused no beginners. And we would have had four years to come up with a literal syntax pun on n00b.

[bishabosha]

here is the relevant doc section to update: https://scala-lang.org/files/archive/spec/3.4/01-lexical-syntax.html#integer-literals

[odersky]

Plus, we should have a short doc page in the docs/_docs/reference pages explaining the feature with a short example. We do that for all features that are new in Scala 3.

[Sporarum]

I was expecting it to get backported to Scala 2, since there is already an implementation targetting it, will this not be the case ?

[som-snytt]

@Sporarum that is likely. scala/scala#10656

[odersky]

But in any case we need a doc page to explain the new feature, whether it will be in Scala 2 or not. It should not be hard...

[Sporarum]

@odersky
Totally agree, and I'll try to do it this weekend, it's more a question of where, and thus in which format ?

[odersky]

I think it should have an entry here:

https://dotty.epfl.ch/docs/reference/index.html

Local directory is docs/_docs/reference.

[SethTisue]

Note that the Scala 2 PR is now merged (for release in Scala 2.13.13).

[Sporarum]

I have added a short reference page, let me know if something is missing

[Sporarum]

I added the line to the second sidebar, and updated the Scala 3 Spec (I mistook the earlier message with one speaking about the Scala 2 Spec)

If it's good like that, let me know and I'll squash my commits together

[Sporarum]

@bishabosha, @sjrd I wasn't sure if I could merge it, so I'll leave you to it

[nicolasstucki]

I noticed we are missing a test for 0b1010l (Long with lower case).