Add Scala 3.6.2 announcement

_posts/2024-11-19-release-notes-3.6.0.md → _posts/2024-12-05-release-notes-3.6.2.md

@@ -1,16 +1,26 @@
 ---
 category: announcement
-permalink: /news/3.6.0
-title: "Scala 3.6.0 is now available!"
+permalink: /news/3.6.2
+title: "Scala 3.6.2 is now available!"
 ---
 
 ![Scala 3.6]({{ site.baseurl }}/resources/img/scala-3.6-launch.jpg)
 
-We're happy to announce the next minor release of Scala - 3.6.0 is finally out!
+We're happy to announce the next minor release of Scala - 3.6.2 is finally out!
 
-# What’s new in 3.6.0?
+# What happend to Scala 3.6.0 and 3.6.1?
 
-Besides multiple bugfixes, this release stabilises multiple experimental features introduced to Scala language after careful review and acceptance by the [Scala Improvement Proposal's Commitee](https://docs.scala-lang.org/sips/). Many of these changes can have a significant impact on the Scala syntax and are introducing new amazing possibilities in writing concise, typesafe as well as easier, and easier to maintain code.
+During the release of 3.6.0-RC1, an accident caused the publishing of artefacts versioned as 3.6.0 to the immutable Maven repository.
+To mitigate possible damage we've released a hotfix release 3.6.1 to prevent automatic tooling from using a broken version of the compiler.
+Versions 3.6.0 (a broken release) and 3.6.1 (a hotfix release) should never be used.
+The incident was described in detail at [Scala 3.6.0 Post Mortem blogpost](https://www.scala-lang.org/news/post-mortem-3.6.0.html).
+
+Scala 3.6.2 should effectively be regarded as "3.6.0" for all intents and purposes.
+We apologize to the Scala users for any inconvenience it might have caused.
+
+# What’s new in Scala 3.6?
+
+Besides multiple bugfixes, this release stabilises multiple experimental features introduced to Scala language after careful review and acceptance by the [Scala Improvement Proposal's Commitee](https://docs.scala-lang.org/sips/). Many of these changes can have a significant impact on the Scala syntax and are introducing new possibilities in writing concise, typesafe as well as easier, and easier to maintain code.
 
 ## SIP-47 - Clause Interleaving
 
@@ -24,71 +34,6 @@ trait DB {
 }
 ```
 
-## SIP-58 - Named Tuples
-
-Another stabilized feature in this release are the Named Tuples. These have been introduced as experimental in Scala 3.5.0 and allowed you to give meaningful names to tuple elements and use those names during constructing, destructuring, and pattern matching.
-
-```scala
-extension [T](seq: Seq[T])
-  def partitionBy(predicate: PartialFunction[T, Boolean]): (matching: Seq[T], unmatched: Seq[T]) =
-    seq.partition(predicate.unapply(_).isDefined)
-
-@main def onlySmallRealNumbers =
-  List(
-    (x = 1, y = 0),
-    (x = 2, y = 3),
-    (x = 0, y = 1),
-    (x = 3, y = 0),
-  ).partitionBy:
-    case (x = real, y = 0) => real < 5
-  .matching.map(_.x)
-  .foreach(println)
-```
-
-This change also introduces improvements to extractors of case classes. You can now define named extractors for a selection of fields, allowing you to unclutter your code from unused variables.
-
-```scala
-case class User(id: Int, name: String, surname: String)
-
-extension (values: Seq[User])
-  //  Collect user IDs of every entry that has the name matching argument
-  def idsWithName(name: String) = values.collect:
-    case User(name = `name`, id = userId) => userId
-```
-
-Last, but not least, named tuples are opening a new paradigm of metaprogramming by letting you compute structural types without need for macros!
-The `Selectable` trait now has a `Fields` type member that can be instantiated to a named tuple.
-
-```scala
-class QueryResult[T](rawValues: Map[String, Any]) extends Selectable:
-  type Fields = NamedTuple.Map[NamedTuple.From[T], Option]
-  def selectDynamic(fieldName: String) = rawValues.get(fieldName)
-
-case class City(zipCode: Int, name: String)
-
-@main def Test =
-  val query: QueryResult[City] = QueryResult(Map("name" -> "Lausanne"))
-  assert(query.name.contains("Lausanne"))
-  assert(query.zipCode.isEmpty)
-```
-
-You can read more about named tuples in the [dedicated section of Scala 3 reference documentation](https://scala-lang.org/api/3.6.0/docs/docs/reference/other-new-features/named-tuples.html).
-
-## SIP-62 - For-Comprehension Improvements
-
-Starting with Scala 3.6.0 you can take advantage of improvements to the for-comprehesnions syntax.
-Major user-facing improvement introduced by [SIP-62](https://docs.scala-lang.org/sips/better-fors.html) is the ability to start a for-comprehension block with aliases:
-
-```scala
-  for
-    a = 1
-    b <- Some(2)
-    c <- doSth(a)
-  yield b + c
-```
-
-It also introduces changes to how your code is desugared by the compiler, leading to a more optimized code by removing some redundant calls.
-
 ## SIP-64 - Improve Syntax for Context Bounds and Givens
 
 This release stabilises the [SIP-64](https://docs.scala-lang.org/sips/sips/typeclasses-syntax.html) introduced as experimental in Scala 3.5.0. These changes provide you with the new syntax for defining type class instances.
@@ -147,13 +92,13 @@ class Set[T] extends Collection:
   override given Order[Element] = ??? // custom implementation provided by the user
 ```
 
-See the updated [Contextual Abstractions](https://scala-lang.org/api/3.6.0/docs/docs/reference/contextual/givens.html) chapter of the Scala 3 reference guide to learn more about these changes.
+See the updated [Contextual Abstractions](https://scala-lang.org/api/3.6.2/docs/docs/reference/contextual/givens.html) chapter of the Scala 3 reference guide to learn more about these changes.
 
 _**Note**: It is important not to confuse changes under SIP-64 with the [experimental modularity improvements](https://dotty.epfl.ch/docs/reference/experimental/typeclasses.html) available under `-language:experimental.modularity` and `-source:future`. These changes are still being developed in the experimental phase and would require SIP committee acceptance before stabilisation.
 
 ## SIP-56 Amendment: Match types extractors follow aliases and singletons
 
-Scala 3.6.0 also stabilises the improvements of match types previously available under `-language:experimental.betterMatchTypeExtractors`. These changes were amending the match type specification and adjusting the implementation of match types under [SIP-56](https://docs.scala-lang.org/sips/match-types-spec.html) to resolve some of the issues reported by users. Under the new rules, it is possible to correctly resolve aliases and singleton types.
+Scala 3.6 also stabilises the improvements of match types previously available under `-language:experimental.betterMatchTypeExtractors`. These changes were amending the match type specification and adjusting the implementation of match types under [SIP-56](https://docs.scala-lang.org/sips/match-types-spec.html) to resolve some of the issues reported by users. Under the new rules, it is possible to correctly resolve aliases and singleton types.
 
 ```scala
 trait A:
@@ -170,6 +115,23 @@ type InvF[Y] = Y match
 def Test = summon[InvF[B] =:= String] // was error: selector B does not uniquely determine parameter x
 ```
 
+## Experimental SIP-62 - For-Comprehension Improvements
+
+Starting with Scala 3.6.2 you can take advantage of improvements to the for-comprehesnions syntax.
+Major user-facing improvement introduced by [SIP-62](https://docs.scala-lang.org/sips/better-fors.html) is the ability to start a for-comprehension block with aliases:
+
+```scala
+//> using options -experimental -language:experimental.betterFors
+@main def betterFors = 
+  for
+    a = 1
+    b <- Some(2)
+    c <- Option.when(a < 5)(10)
+  yield b * c
+```
+
+It also introduces changes to how your code is desugared by the compiler, leading to a more optimized code by removing some redundant calls.
+
 ## Experimental SIP-57 - Replace non-sensical `@unchecked` annotations
 
 One of the new, experimental, features is the implementation of [SIP-57](https://docs.scala-lang.org/sips/replace-nonsensical-unchecked-annotation.html) introducing a `runtimeChecked` extension method replacing some usages of `@unchecked` annotation using a more convenient syntax. A common use case for `runtimeChecked` is to assert that a pattern will always match, either for convenience or because there is a known invariant that the types can not express.
@@ -188,7 +150,7 @@ val Some(appVersion) = config.get("appVersion").runtimeChecked
 
 ## Switch mapping of context bounds to using clauses
 
-Until Scala 3.6.0 context bound parameters were always desugared to `implicit` arguments, starting with 3.6.0 these would be mapped to `using` parameters instead.
+Until Scala 3.6 context bound parameters were always desugared to `implicit` arguments, starting with Scala 3.6 these would be mapped to `using` parameters instead.
 This change should not affect the majority of users, however, it can lead to differences in how implicits are resolved.
 Resolution of implicits can slightly differ depending on whether we're requesting them using `implicit` or `using` parameter, or depending on whether they were defined using `implicit` or `given` keywords. The special behaviours were introduced to smoothen migration from Scala 2 to brand new implicits resolution in Scala 3.
 This change might also affect some of the projects that use compiler plugins or macros to inspect the implicit argument lists of the function calls - these might require some minor fixes, eg. when filtering symbols by their flags.
@@ -199,7 +161,7 @@ This change might also affect some of the projects that use compiler plugins or
 
 In the [Scala 3.5.0 release notes](https://scala-lang.org/blog/2024/08/22/scala-3.5.0-released.html) we've announced upcoming changes to givens, due to their peculiar problem with prioritization. Currently, the compiler always tries to select the instance with the most specific subtype of the requested type. In the future, it would change to always selecting the instance with the most general subtype that satisfies the context-bound.
 
-Starting from Scala 3.6.0, code whose behaviour can differ between new and old rules (ambiguity on new, passing on old, or vice versa) will emit warnings, but the old rules will still be applied.
+Starting from Scala 3.6, code whose behaviour can differ between new and old rules (ambiguity on new, passing on old, or vice versa) will emit warnings, but the old rules will still be applied.
 Running the compiler with `-source:3.5` will allow you to temporarily keep using the old rules; with `-source:3.7` or `-source:future` the new scheme will be used.
 
 For the detailed motivation of changes with examples of code that will be easier to write and understand, see our recent blog post - [Upcoming Changes to Givens in Scala 3.7]({{ site.baseurl }}/2024/08/19/given-priority-change-3.7.html).
@@ -217,16 +179,76 @@ Let's take the following example:
 ```
 
 Reordering the fields is binary-compatible but it might affect the meaning of `@Annotation(1)`
-Starting from Scala 3.6.0, named arguments are required for Java-defined annotations.
+Starting from Scala 3.6, named arguments are required for Java-defined annotations.
 The compiler can provide you with automatic rewrites introducing now required names, using `-source:3.6-migration, -rewrite` flags. The rewrites are done on a best-effort basis and should be inspected for correctness by the users.
 
+## Experimental SIP-58 - Named Tuples
+
+Named Tuples have been introduced as experimental in Scala 3.5.0. This feature is now ready to be tested, but is not yet stablized.
+We encourage you to try named tuples and to report your feedback [on the public forum](https://contributors.scala-lang.org/t/pre-sip-named-tuples).
+Named Tuples allow you to give meaningful names to tuple elements and use those names during constructing, destructuring, and pattern matching.
+
+```scala
+//> using options -experimental -language:experimental.namedTuples
+extension [T](seq: Seq[T])
+  def partitionBy(predicate: PartialFunction[T, Boolean]): (matching: Seq[T], unmatched: Seq[T]) =
+    seq.partition(predicate.unapply(_).isDefined)
+
+@main def onlySmallRealNumbers =
+  List(
+    (x = 1, y = 0),
+    (x = 2, y = 3),
+    (x = 0, y = 1),
+    (x = 3, y = 0),
+  ).partitionBy:
+    case (x = real, y = 0) => real < 5
+  .matching.map(_.x)
+  .foreach(println)
+```
+
+This change also introduces improvements to extractors of case classes. You can now define named extractors for a selection of fields, allowing you to unclutter your code from unused variables.
+
+```scala
+//> using options -experimental -language:experimental.namedTuples
+case class User(id: Int, name: String, surname: String)
+
+extension (values: Seq[User])
+  //  Collect user IDs of every entry that has the name matching argument
+  def idsWithName(name: String) = values.collect:
+    case User(name = `name`, id = userId) => userId
+```
+
+Last, but not least, named tuples are opening a new paradigm of metaprogramming by letting you compute structural types without need for macros!
+The `Selectable` trait now has a `Fields` type member that can be instantiated to a named tuple.
+
+```scala
+//> using options -experimental -language:experimental.namedTuples
+class QueryResult[T](rawValues: Map[String, Any]) extends Selectable:
+  type Fields = NamedTuple.Map[NamedTuple.From[T], Option]
+  def selectDynamic(fieldName: String) = rawValues.get(fieldName)
+
+case class City(zipCode: Int, name: String)
+
+@main def Test =
+  val query: QueryResult[City] = QueryResult(Map("name" -> "Lausanne"))
+  assert(query.name.contains("Lausanne"))
+  assert(query.zipCode.isEmpty)
+```
+
+You can read more about named tuples in the [dedicated section of Scala 3 reference documentation](https://scala-lang.org/api/3.6.2/docs/docs/reference/experimental/named-tuples.html).
+
 # What’s next?
-<!-- TODO: Fill me -->
+
+The Scala 3.6.2 will be followed by at least 2 patch releases, during which we will focus on bug fixes and improvements to experimental features based on your feedback.
+You can expect Scala 3.6.3 to be released in the middle of January followed by 3.6.4 by the end of Q1 2025.
+In Q2 2025 we're planning a new minor release of Scala 3.7 that might bring stabilisation to some of the experimental features. We are encouraging you to test out the experimental features mentioned in this article and share your feedback with the Scala team.
+
+Currently, we are also preparing a Scala 3.3.5 LTS patch release - it would include all backportable changes introduced until Scala 3.5.2. It should be released in January 2025.
 
 # Contributors
 
 Thank you to all the contributors who made this release possible 🎉
 
-According to git shortlog -sn --no-merges 3.5.2..3.6.0 these are:
+According to git shortlog -sn --no-merges 3.5.2..3.6.2 these are:
 
 <!-- TODO: Fill me -->