Add docs on changed features #2592
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| Lazy val initialization no longer guarantees safe publishing. This change was done | ||
| to avid the performance overhead of thread synchonization because many lazy vals are only used in a single-threaded context. |
| once it is assigned. | ||
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| The [ScalaFix](https://scalacenter.github.io/scalafix/) rewrite tool | ||
| as well as Dotty's own `-migration` option will rewrite all normal |
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-migration is only for migration warnings, to get dotty to rewrite stuff you need -language:Scala2 -rewrite.
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It might be best to not mention the dotty internal rewrite mechanism until we know what we want to do with it.
| Previously, Scala supported structural types by means of | ||
| reflection. This is problematic on other platforms, because Scala's | ||
| reflection is JVM-based. Consequently, Scala.js and Scala.native don't | ||
| dupport structural types fully. The reflction based implementation is |
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Typo: dupport -> support
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| 2. Implicit parameters may not have singleton types. | ||
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| /*!*/ def f(implicit x: y.type) // error `y.type` not allowed as type of implicit |
| @volatile lazy val x = expr | ||
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| it is guaranteed that readers of a lazy val will see the value of `x` | ||
| once it is assigned. |
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What exactly is the difference in behavior between volatile and non-volatile lazy vals?
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| /*!*/ case List(1, 2, xs @ _*) // syntax error | ||
| /*!*/ case List(1, 2, _*) => ... // syntax error | ||
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When developing Scalameta 2.x that's supposed to crosscompile against 2.x and 3.x, I found this to be an unfortunate problem. There's currently no way to write crosscompilable code that contains sequence wildcards. Can something be done with this?
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@xeno-by AFAIK, we support both syntaxes under -language:Scala2
#1059
On 30 May 2017 01:14:25 Eugene Burmako [email protected] wrote:
xeno-by commented on this pull request.
+The syntax of vararg patterns has changed. In the new syntax one
+writes varargs in patterns exactly like one writes them in
+expressions, using a: _*type annotation:
+
- xs match {
case List(1, 2, xs: _*) => println(xs) // binds xscase List(1, _ : _*) => // wildcard pattern- }
+The old syntax, which is shorter but less regular, is no longer
+supported:
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- /!/ case List(1, 2, xs @ _*) // syntax error
- /!/ case List(1, 2, _*) => ... // syntax error
When developing Scalameta 2.x that's supposed to crosscompile against 2.x
and 3.x, I found this to be an unfortunate problem. There's currently no
way to write crosscompilable code that contains sequence wildcards. Can
something be done with this?--
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