Address Seth's comments

Author: biboudis

docs/blog/_posts/2019-12-20-21th-dotty-milestone-release.md

@@ -8,10 +8,10 @@ date: 2019-12-21
 
 Greetings and we wish you Merry Christmas 🎄!
 
-We are excited to announce 0.21.0-RC1 of Scala 3. In this version we add support
-for non-nullable reference types and a flow-sensitive analysis that work
-complementary. We present new syntax for given extensions, matches and pattern
-matching over quotes. We are also happy to announce that SemanticDB generation
+We are excited to announce 0.21.0-RC1 of Dotty. In this version we add support
+for non-nullable reference types, supported by flow-sensitive analysis. We
+present new syntax for given extensions, matches and pattern matching over
+quotes. We are also happy to announce that SemanticDB generation
 is now supported within the compiler, this will eventually enable Metals to support Dotty!
 
 # Feature Complete!
@@ -29,7 +29,7 @@ This means that with this release we stop adding new features and we focus on:
 - documentation improvements 📕
 - education 👨‍🏫
 
-Being feature complete does not mean that every detail of Scala-3 is cast in
+Being feature complete does not mean that every detail of Scala 3 is cast in
 stone yet. Some details can still change, or be enabled conditionally, or even
 be dropped entirely. That will depend on the additional experience we gain over
 the next months, in particular the feedback we receive from the community and
@@ -41,7 +41,7 @@ For an overview of the feature envelope that Scala 3 carries you can read our
 For a more detailed discussion on the transition to Scala 3 you can read the
 [Scala 2 roadmap update: The road to Scala 3](https://www.scala-lang.org/2019/12/18/road-to-scala-3.html).
 
-### Community-build
+### Community build
 
 Being feature complete doesn't mean that development slows down. On the contrary!
 It means that we can now put the Scala 3 compiler under heavy load, getting it
@@ -62,7 +62,7 @@ from the root of the dotty repo.
 Firstly thank you for all the hard work in issue reporting! Being feature complete means that our
 issue tracker will now be more important than ever. We encourage you to stress
 the compiler and report self contained test-cases! Bug minimization is hard and
-a form of art! Help us unearth those nasty bugs! ✊
+a art form! Help us unearth those nasty bugs! ✊
 
 Last but not least we restate the mission of Scala 3. Scala has pioneered the
 fusion of object-oriented and functional programming in a typed setting and Scala 3
@@ -129,14 +129,42 @@ val s2: String|Null = ???
 if (s != null && s2 != null) // s: String and s2: String
 ```
 
-but also in a short-circuting manner:
+but also in a short-circuiting manner:
 
 ```scala
 val s: String|Null = ???
 
 if (s != null && s.length > 0) // s: String in `s.length > 0`
 ```
 
+To support Java Interop under explicit nulls we provide an alias for `Null`
+called `UncheckedNull`. The compiler can load Java classes in two ways: from
+source or from bytecode. In either case, when a Java class is loaded, we "patch"
+the type of its members to reflect that Java types remain implicitly nullable.
+
+An additional value of `UncheckedNull` (on the Scala side) is that we
+effectively support method chaining on Java-returned values. e.g.,
+
+```scala
+val s2: String = someJavaMethod().trim().substring(2).toLowerCase()
+```
+
+as opposed to:
+
+```scala
+val ret = someJavaMethod()
+val s2 = if (ret != null) {
+  val tmp = ret.trim()
+  if (tmp != null) {
+    val tmp2 = tmp.substring(2)
+    if (tmp2 != null) {
+      tmp2.toLowerCase()
+    }
+  }
+}
+// Additionally, we need to handle the `else` branches.
+```
+
 For more info refer to the docs on [Explicit Nulls](https://dotty.epfl.ch/docs/reference/other-new-features/explicit-nulls.html).
 
 ## New syntax for given instances defining extension methods
@@ -178,7 +206,7 @@ Using present given syntax, it can seem awkward to define parameterised instance
 ```scala
 given listOrd[T](given Ord[T]): Ord[List[T]] ...
 ```
-it's particululary unfortunate for anonymous given instances:
+it's particularly unfortunate for anonymous given instances:
 ```scala
 given [T](given Ord[T]): Ord[List[T]] ...
 ```
@@ -224,7 +252,7 @@ After a period of experimentation, either the new or old way will remain.
 ## New match syntax
 
 We introduce an improved treatment of `match`. We reintroduce `match` as an
-alphanumeric, left-associative, infix operator that can support chain matches:
+alphanumeric, left-associative, infix operator that can support chained matches:
 
 ```scala
 xs match {
@@ -245,9 +273,9 @@ xs.match {
 }
 ```
 
-You can read more on our docs [Match Expressions](https://dotty.epfl.ch/docs/reference/changed-features/match-syntax.html) and on the interesting discussions on [contributors](https://contributors.scala-lang.org/t/pre-sip-demote-match-keyword-to-a-method/2137/2).
+You can read more in our docs [Match Expressions](https://dotty.epfl.ch/docs/reference/changed-features/match-syntax.html) and on the interesting discussions in [contributors](https://contributors.scala-lang.org/t/pre-sip-demote-match-keyword-to-a-method/2137/2).
 
-## New quoted pattern matching
+## Metaprogramming: New quoted pattern matching
 
 We introduce a high-level API to deconstruct or extract values out of `Expr`
 using pattern matching. It consists of high-level extractors for getting static