Ruby Issue Tracking System

06/29/2026

04:35 AM Ruby Feature #22132: Scala-like for comprehensions

ko1 (Koichi Sasada) wrote in #note-8:
> just curious: `for ... then` for single iterator will makes `map` behavior like that?
Yes, a single iterator `for ... then` desugars to `map`.
That's why we need `then` instead of `do`.
> .... shugo (Shugo Maeda)

06/27/2026

10:27 AM Ruby Feature #22132: Scala-like for comprehensions

Thanks for the feedback.
I agree that "you rarely need `for`, think in Enumerable" is core to how Ruby is taught, and I don't want to weaken that.
But I think the "what is Enumerable missing?" framing misses the point here. This pr... shugo (Shugo Maeda)

06/26/2026

11:49 PM Ruby Misc #22107: DevMeeting-2026-07-09

* [Feature #22132] Scala-like for comprehensions
* Are `then` and `when` acceptable? (`yield` and `if` are not usable due to grammar conflicts)
* Should a comprehension scope loop variables, or leak them like `for ... do`?
* I th... shugo (Shugo Maeda)

11:30 PM Ruby Feature #22132 (Open): Scala-like for comprehensions

## Abstract
How about adding an expression form of `for` that desugars into nested `flat_map`/`map` and `filter` calls.
Here's an example, which computes all pairs of numbers between `0` and `n-1` whose sum is equal to a given valu... shugo (Shugo Maeda)

06/24/2026

12:42 AM Ruby Feature #22097: Add Proc#with_refinements

Thank you for your feedback, and I'm glad to hear your concerns are mostly addressed.
Eregon (Benoit Daloze) wrote in #note-16:
> I'm not sure it's really needed though and might be surprising, is it needed?
`with_refinements` is seman... shugo (Shugo Maeda)

06/14/2026

11:44 AM Ruby Feature #22097: Add Proc#with_refinements

Now `Proc#with_refinements` can be called in non-main Ractors:
https://github.com/ruby/ruby/pull/17248/changes/4db090a95939e92189bfcdfe096777950eb0b869
Memo access is synchronized with `RB_VM_LOCKING()`.
In single-Ractor mode it takes n... shugo (Shugo Maeda)

06/12/2026

07:02 PM Ruby Revision 1940cd56 (git): compile.c: fix dupstring-of-Regexp from folded /o regexp

The peephole optimizer folds "dupstring str; toregexp" (and the
dupchilledstring / putobject-string variants) into a single
literal-push by compiling the Regexp at compile time and replacing the
operand with it. It replaced the operand ... shugo (Shugo Maeda)

08:15 AM Ruby Bug #22103 (Closed): Constant-folded /o regexp crashes with dupstring of a Regexp

Applied in changeset commit:git|0f211465887a601a9a1eb1b8d4f5174c852b4939.
----------
compile.c: fix dupstring-of-Regexp from folded /o regexp
The peephole optimizer folds "dupstring str; toregexp" (and the
dupchilledstring / putobject-... shugo (Shugo Maeda)

08:15 AM Ruby Revision 0f211465 (git): compile.c: fix dupstring-of-Regexp from folded /o regexp

The peephole optimizer folds "dupstring str; toregexp" (and the
dupchilledstring / putobject-string variants) into a single
literal-push by compiling the Regexp at compile time and replacing the
operand with it. It replaced the operand ... shugo (Shugo Maeda)

07:31 AM Ruby Misc #22107: DevMeeting-2026-07-09

* [Feature #22097] Add Proc#with_refinements
* For maintainability, I've replaced the hand-written iseq deep-copy with an in-memory IBF dump+load round-trip
* Should it warn or raise when called with different modules for the same bl... shugo (Shugo Maeda)