Merge branch 'travissarles-master' of github.com:scala/scala.github.com into travissarles-master

heathermiller · heathermiller · commit b738eaebe281 · 2017-07-19T16:06:42.000+02:00
diff --git a/Gemfile.lock b/Gemfile.lock
@@ -1,61 +1,79 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.2.7)
+    activesupport (4.2.8)
       i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
-    addressable (2.4.0)
+    addressable (2.5.1)
+      public_suffix (~> 2.0, >= 2.0.2)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
-    coffee-script-source (1.10.0)
+    coffee-script-source (1.12.2)
     colorator (1.1.0)
-    ethon (0.9.1)
+    ethon (0.10.1)
       ffi (>= 1.3.0)
     execjs (2.7.0)
-    faraday (0.9.2)
+    faraday (0.12.1)
       multipart-post (>= 1.2, < 3)
-    ffi (1.9.14)
+    ffi (1.9.18)
     forwardable-extended (2.6.0)
-    gemoji (2.1.0)
-    github-pages (104)
-      activesupport (= 4.2.7)
-      github-pages-health-check (= 1.2.0)
-      jekyll (= 3.3.0)
+    gemoji (3.0.0)
+    github-pages (143)
+      activesupport (= 4.2.8)
+      github-pages-health-check (= 1.3.4)
+      jekyll (= 3.4.5)
       jekyll-avatar (= 0.4.2)
       jekyll-coffeescript (= 1.0.1)
-      jekyll-feed (= 0.8.0)
+      jekyll-default-layout (= 0.1.4)
+      jekyll-feed (= 0.9.2)
       jekyll-gist (= 1.4.0)
-      jekyll-github-metadata (= 2.2.0)
+      jekyll-github-metadata (= 2.4.0)
       jekyll-mentions (= 1.2.0)
+      jekyll-optional-front-matter (= 0.1.2)
       jekyll-paginate (= 1.1.0)
-      jekyll-redirect-from (= 0.11.0)
-      jekyll-sass-converter (= 1.3.0)
-      jekyll-seo-tag (= 2.1.0)
-      jekyll-sitemap (= 0.12.0)
+      jekyll-readme-index (= 0.1.0)
+      jekyll-redirect-from (= 0.12.1)
+      jekyll-relative-links (= 0.4.1)
+      jekyll-sass-converter (= 1.5.0)
+      jekyll-seo-tag (= 2.2.3)
+      jekyll-sitemap (= 1.0.0)
       jekyll-swiss (= 0.4.0)
-      jemoji (= 0.7.0)
-      kramdown (= 1.11.1)
+      jekyll-theme-architect (= 0.0.4)
+      jekyll-theme-cayman (= 0.0.4)
+      jekyll-theme-dinky (= 0.0.4)
+      jekyll-theme-hacker (= 0.0.4)
+      jekyll-theme-leap-day (= 0.0.4)
+      jekyll-theme-merlot (= 0.0.4)
+      jekyll-theme-midnight (= 0.0.4)
+      jekyll-theme-minimal (= 0.0.4)
+      jekyll-theme-modernist (= 0.0.4)
+      jekyll-theme-primer (= 0.3.0)
+      jekyll-theme-slate (= 0.0.4)
+      jekyll-theme-tactile (= 0.0.4)
+      jekyll-theme-time-machine (= 0.0.4)
+      jekyll-titles-from-headings (= 0.2.0)
+      jemoji (= 0.8.0)
+      kramdown (= 1.13.2)
       liquid (= 3.0.6)
       listen (= 3.0.6)
       mercenary (~> 0.3)
-      minima (= 2.0.0)
+      minima (= 2.1.1)
       rouge (= 1.11.1)
       terminal-table (~> 1.4)
-    github-pages-health-check (1.2.0)
+    github-pages-health-check (1.3.4)
       addressable (~> 2.3)
       net-dns (~> 0.8)
       octokit (~> 4.0)
-      public_suffix (~> 1.4)
+      public_suffix (~> 2.0)
       typhoeus (~> 0.7)
-    html-pipeline (2.4.2)
+    html-pipeline (2.6.0)
       activesupport (>= 2)
       nokogiri (>= 1.4)
-    i18n (0.7.0)
-    jekyll (3.3.0)
+    i18n (0.8.6)
+    jekyll (3.4.5)
       addressable (~> 2.4)
       colorator (~> 1.0)
       jekyll-sass-converter (~> 1.0)
@@ -70,70 +88,110 @@ GEM
       jekyll (~> 3.0)
     jekyll-coffeescript (1.0.1)
       coffee-script (~> 2.2)
-    jekyll-feed (0.8.0)
+    jekyll-default-layout (0.1.4)
+      jekyll (~> 3.0)
+    jekyll-feed (0.9.2)
       jekyll (~> 3.3)
     jekyll-gist (1.4.0)
       octokit (~> 4.2)
-    jekyll-github-metadata (2.2.0)
+    jekyll-github-metadata (2.4.0)
       jekyll (~> 3.1)
       octokit (~> 4.0, != 4.4.0)
     jekyll-mentions (1.2.0)
       activesupport (~> 4.0)
       html-pipeline (~> 2.3)
       jekyll (~> 3.0)
+    jekyll-optional-front-matter (0.1.2)
+      jekyll (~> 3.0)
     jekyll-paginate (1.1.0)
-    jekyll-redirect-from (0.11.0)
-      jekyll (>= 2.0)
-    jekyll-sass-converter (1.3.0)
-      sass (~> 3.2)
-    jekyll-seo-tag (2.1.0)
+    jekyll-readme-index (0.1.0)
+      jekyll (~> 3.0)
+    jekyll-redirect-from (0.12.1)
+      jekyll (~> 3.3)
+    jekyll-relative-links (0.4.1)
+      jekyll (~> 3.3)
+    jekyll-sass-converter (1.5.0)
+      sass (~> 3.4)
+    jekyll-seo-tag (2.2.3)
       jekyll (~> 3.3)
-    jekyll-sitemap (0.12.0)
+    jekyll-sitemap (1.0.0)
       jekyll (~> 3.3)
     jekyll-swiss (0.4.0)
+    jekyll-theme-architect (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-cayman (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-dinky (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-hacker (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-leap-day (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-merlot (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-midnight (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-minimal (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-modernist (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-primer (0.3.0)
+      jekyll (~> 3.3)
+    jekyll-theme-slate (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-tactile (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-theme-time-machine (0.0.4)
+      jekyll (~> 3.3)
+    jekyll-titles-from-headings (0.2.0)
+      jekyll (~> 3.3)
     jekyll-watch (1.5.0)
       listen (~> 3.0, < 3.1)
-    jemoji (0.7.0)
+    jemoji (0.8.0)
       activesupport (~> 4.0)
-      gemoji (~> 2.0)
+      gemoji (~> 3.0)
       html-pipeline (~> 2.2)
       jekyll (>= 3.0)
-    json (1.8.6)
-    kramdown (1.11.1)
+    kramdown (1.13.2)
     liquid (3.0.6)
     listen (3.0.6)
       rb-fsevent (>= 0.9.3)
       rb-inotify (>= 0.9.7)
     mercenary (0.3.6)
     mini_portile2 (2.1.0)
-    minima (2.0.0)
-    minitest (5.9.1)
+    minima (2.1.1)
+      jekyll (~> 3.3)
+    minitest (5.10.2)
     multipart-post (2.0.0)
     net-dns (0.8.0)
     nokogiri (1.6.8.1)
       mini_portile2 (~> 2.1.0)
-    octokit (4.4.1)
-      sawyer (~> 0.7.0, >= 0.5.3)
+    octokit (4.7.0)
+      sawyer (~> 0.8.0, >= 0.5.3)
     pathutil (0.14.0)
       forwardable-extended (~> 2.6)
-    public_suffix (1.5.3)
-    rb-fsevent (0.9.8)
-    rb-inotify (0.9.7)
-      ffi (>= 0.5.0)
+    public_suffix (2.0.5)
+    rb-fsevent (0.10.2)
+    rb-inotify (0.9.10)
+      ffi (>= 0.5.0, < 2)
     rouge (1.11.1)
     safe_yaml (1.0.4)
-    sass (3.4.22)
-    sawyer (0.7.0)
-      addressable (>= 2.3.5, < 2.5)
-      faraday (~> 0.8, < 0.10)
-    terminal-table (1.7.3)
-      unicode-display_width (~> 1.1.1)
-    thread_safe (0.3.5)
+    sass (3.5.1)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+    sawyer (0.8.1)
+      addressable (>= 2.3.5, < 2.6)
+      faraday (~> 0.8, < 1.0)
+    terminal-table (1.8.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    thread_safe (0.3.6)
     typhoeus (0.8.0)
       ethon (>= 0.8.0)
-    tzinfo (1.2.2)
+    tzinfo (1.2.3)
       thread_safe (~> 0.1)
-    unicode-display_width (1.1.1)
+    unicode-display_width (1.3.0)
 
 PLATFORMS
   ruby
@@ -143,4 +201,4 @@ DEPENDENCIES
   jekyll-redirect-from
 
 BUNDLED WITH
-   1.14.6
+   1.15.1
diff --git a/sips/pending/_posts/2017-07-12-right-associative-by-name-operators.md b/sips/pending/_posts/2017-07-12-right-associative-by-name-operators.md
@@ -0,0 +1,90 @@
+---
+layout: sip
+discourse: true
+title: SIP-NN - Right-Associative By-Name Operators
+---
+
+**By: Stefan Zeiger**
+
+## History
+
+| Date          | Version       |
+|---------------|---------------|
+| Jul 12th 2017 | Initial Draft |
+
+## Motivation
+
+Scala allows the definition of right-associative by-name operators but the desugaring, as
+currently defined, forces the arguments, thus effectively making them by-value. This has
+been recognized as a [bug](https://github.com/scala/bug/issues/1980) since 2009.
+
+## Motivating Examples
+
+Apart from the examples mentioned in and linked to [scala/bug#1980](https://github.com/scala/bug/issues/1980),
+this has recently come up as a [problem for the collections library redesign](https://github.com/scala/collection-strawman/issues/127)
+for Scala 2.13.
+
+Scala 2.12 has a `Stream` type with a lazy tail and a strict head element. Thanks to a clever
+[hack](https://github.com/scala/scala/blob/9ab72a204ff3070ffabc3c06f3d381999da43fcd/src/library/scala/collection/immutable/Stream.scala#L1115-L1133)
+right-associative by-name operators can work well enough for `Stream`:
+
+    scala> def f(i: Int) = { println("Generating "+i); i }
+    f: (i: Int)Int
+
+    scala> f(1) #:: f(2) #:: f(3) #:: Stream.empty
+    Generating 1
+    res0: scala.collection.immutable.Stream[Int] = Stream(1, ?)
+
+The `LazyList` type proposed for the new collections library is supposed to be lazy in the head and tail.
+This cannot be supported with the existing hack (which always forces the first element in the chain), so we need
+a proper fix at the language level.
+
+## Design
+
+The desugaring of binary operators is currently defined in the spec as:
+
+> A left-associative binary
+> operation `e1 op e2` is interpreted as `e1.op(e2)`. If `op` is
+> right-associative, the same operation is interpreted as
+> `{ val x=e1; e2.op(x) }`, where `x` is a fresh name.
+
+It should be changed to:
+
+> A left-associative binary
+> operation `e1 op e2` is interpreted as `e1.op(e2)`. If `op` is
+> right-associative and its parameter is passed by name, the same operation is interpreted as
+> `e2.op(e1)`. If `op` is right-associative and its parameter is passed by value,
+> it is interpreted as `{ val x=e1; e2.op(x) }`, where `x` is a fresh name.
+
+This means that all by-value parameters are still forced from left to right but by-name
+parameters are not forced anymore. They now behave the same way in operator syntax as they
+would when using standard method call syntax.
+
+## Implementation
+
+A complete implementation for Scala 2.13 is provided in [scala/scala#5969](https://github.com/scala/scala/pull/5969).
+
+## Counter-Examples
+
+No change of type inference semantics is implied by the new desugaring. In particular, all parameters to
+right-associative operators are still type-checked without an expected type in the current implementation.
+
+It may be desirable to use an expected type, like for a method call, but that is orthogonal to this proposal
+and would necessarily apply equally to by-name and by-value parameters. In the case of overloaded
+operators it cannot be determined whether the parameter is by-name or by-value without type-checking the
+argument first.
+
+## Drawbacks
+
+- This constitutes a silent change in semantics for existing code. Since the current semantics are essentially
+  broken the likelihood of affecting existing code negatively are low.
+
+- Macros and tooling that works at the Scala AST level may need to be adapted to the new desugaring. This is also
+  unlikely because the new desugaring produces currently legal Scala code that could have been manually written in
+  the same way.
+
+## Alternatives
+
+As mentioned above, the current `Stream`
+[hack](https://github.com/scala/scala/blob/9ab72a204ff3070ffabc3c06f3d381999da43fcd/src/library/scala/collection/immutable/Stream.scala#L1115-L1133)
+can work around this problem in some cases but not all.
diff --git a/tutorials/tour/_posts/2017-02-13-mixin-class-composition.md b/tutorials/tour/_posts/2017-02-13-mixin-class-composition.md
@@ -71,8 +71,8 @@ We would like to combine the functionality of `StringIterator` and `RichIterator
 
 ```tut
 object StringIteratorTest extends App {
-  class Iter extends StringIterator(args(0)) with RichIterator
-  val iter = new Iter
+  class RichStringIter extends StringIterator(args(0)) with RichIterator
+  val iter = new RichStringIter
   iter foreach println
 }
 ```
diff --git a/tutorials/tour/_posts/2017-02-13-pattern-matching.md b/tutorials/tour/_posts/2017-02-13-pattern-matching.md
@@ -114,7 +114,7 @@ In the `case Email(email, _, _) if importantPeopleInfo.contains(email)`, the pat
 You can match on the type like so:
 ```tut
 abstract class Device
-case class Phone(model: String) extends Device{
+case class Phone(model: String) extends Device {
   def screenOff = "Turning screen off"
 }
 case class Computer(model: String) extends Device {
diff --git a/tutorials/tour/_posts/2017-02-13-traits.md b/tutorials/tour/_posts/2017-02-13-traits.md
@@ -60,7 +60,7 @@ iterator.next()  // prints 1
 This `IntIterator` class takes a parameter `to` as an upper bound. It `extends Iterator[Int]` which means that the `next` method must return an Int.
 
 ## Subtyping
-Subtypes of traits can be used where a the trait is required.
+Where a given trait is required, a subtype of the trait can be used instead.
 ```tut
 import scala.collection.mutable.ArrayBuffer
 

Original file line number	Diff line number	Diff line change
@@ -114,7 +114,7 @@ In the `case Email(email, _, _) if importantPeopleInfo.contains(email)`, the pat
`114`	`114`	`You can match on the type like so:`
`115`	`115`	```tut
`116`	`116`	`abstract class Device`
`117`		`-case class Phone(model: String) extends Device{`
	`117`	`+case class Phone(model: String) extends Device {`
`118`	`118`	`def screenOff = "Turning screen off"`
`119`	`119`	`}`
`120`	`120`	`case class Computer(model: String) extends Device {`