Add blogpost for 0.12.0-RC1 and 0.11.0

Author: biboudis

docs/blog/_posts/2019-01-17-12th-dotty-milestone-release.md

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+---
+layout: blog-page
+title: Announcing Dotty 0.12.0-RC1
+author: Aggelos Biboudis
+authorImg: /images/aggelos.jpg
+date: 2019-01-21
+---
+
+Happy New Year to all with the first release of Dotty for 2019! ✨🎊🎉
+
+Today we are excited to release the version 0.12.0-RC1 of the Dotty compiler. 
+This release serves as a technology preview that demonstrates new language features and the
+compiler supporting them.
+
+Dotty is the project name for technologies that are considered for inclusion in Scala 3. Scala has
+pioneered the fusion of object-oriented and functional programming in a typed setting. Scala 3 will
+be a big step towards realising the full potential of these ideas. Its main objectives are to
+
+- become more opinionated by promoting programming idioms we found to work well,
+- simplify where possible,
+- eliminate inconsistencies and surprising behaviours,
+- build on strong foundations to ensure the design hangs well together,
+- consolidate language constructs to improve the language’s consistency, safety, ergonomics, and
+  performance.
+
+You can learn more about Dotty on our [website](https://dotty.epfl.ch).
+
+<!--more-->
+
+This is our 12th scheduled release according to our
+[6-week release schedule](https://dotty.epfl.ch/docs/usage/version-numbers.html).
+
+## What’s new in the 0.12.0-RC1 technology preview?
+
+### Extension Methods
+
+We are excited to announce that extension methods are now offered through dedicated language support!
+Extension methods allow one to add methods to a type after the type is defined and up until now they were encoded through the powerful mechanism of implicits. 
+Previously, one had to place the desired method in the trait with the receiver object to extend, as part of the parameter list. 
+The infix-ness of the method was being restored by manually writing the implicit class, resolving `implicitly` that extended object. 
+
+Now, in Dotty we can express an extension method by writing the method and prepending its name with the type to be extended. 
+
+```scala
+case class Circle(x: Double, y: Double, radius: Double)
+
+def (c: Circle) circumference: Double = c.radius * math.Pi * 2
+```
+
+Read the [relevant documentation](https://dotty.epfl.ch/docs/reference/other-new-features/extension-methods.html) about generic extension methods, higher-kinded extension methods and more.
+
+### TASTy Reflect goodies
+
+We implement a new decompiler for TASTy files and we also offer a new VS Code Extension. 
+The decompiler allows to view both decompiled scala source code and the pretty printed TASTy tree when opening a .tasty file. 
+The feature is similar to opening .class files in IntelliJ.
+
+![]({{ site.baseurl }}/images/dotty-ide/decompiler.png "Decompiler")
+
+The decompiler can be invoked with the corresponding flag: `dotc -decompile xyz.tasty`.
+
+On the programmatic side of TASTy we are rolling out changes according to our plan discussed at [Macros: The Plan for Scala 3](https://www.scala-lang.org/blog/2018/04/30/in-a-nutshell.html). 
+In this release, we make progress following the _Next Steps_ of the aforementioned blogpost by offering constructors that work directly with reflect trees. 
+Consequently, TASTy extractors meet their dual, TASTy constructors!
+We also connect the new lower-level reflection layer to the existing principled macro system based on quotes and splices offering, two new expression methods for `Expr[T]`:
+
+- `unseal` that unseals an `Expr[T]` (non traversable code) into a `Term` and
+- `seal` that seals back a `Term` into an `Expr[T]`. 
+
+Read the [relevant documentation](https://dotty.epfl.ch/docs/reference/other-new-features/tasty-reflect.html) to learn how to go from quotes and splices to TASTys Reflect trees and back .
+
+### Alignments with the Scala Improvement Process
+
+In this version we improve the implementation of by-name implicits making it compliant with the [By-name Implicits](https://docs.scala-lang.org/sips/byname-implicits.html) SIP and we implement the `ValueOf` operator which yields the unique value of types with a single inhabitant, effectively syncing it up with the [Literal-Based Singleton Types](https://docs.scala-lang.org/sips/42.type.html) SIP.
+
+### Improvements to GADT support
+
+In this release, we're also rolling out the first batch of improvements to GADT support - namely, variable unification. 
+To keep it short, from knowing that `A <: B` and `B <: A`, we can now deduce that `A = B`, and from `A = B` and `B <: C` we deduce that `A <: C`. 
+This kind of reasoning is necessary for many advanced GADT usages!
+
+### And much more!
+
+Please read our [release notes](https://github.com/lampepfl/dotty/releases/tag/0.12.0-RC1)
+for more details!
+
+## Trying out Dotty
+
+### sbt
+
+You can set up a new sbt project with Dotty as the compiler by running:
+
+```shell
+sbt new lampepfl/dotty.g8
+```
+
+For more details on using Dotty with sbt, see the
+[example project](https://github.com/lampepfl/dotty-example-project).
+
+### [Mill](http://www.lihaoyi.com/mill/)
+
+The Mill build tool version 0.2.6 introduced experimental support for Dotty. For more details on
+using Dotty with Mill, see the
+[example project](https://github.com/lampepfl/dotty-example-project/tree/mill).
+
+### IDE support
+
+Start using the Dotty IDE in any Dotty project by following
+the [IDE guide](https://dotty.epfl.ch/docs/usage/ide-support.html).
+
+### Standalone installation
+
+Releases are available for download on the _Releases_
+section of the Dotty repository:
+[https://github.com/lampepfl/dotty/releases](https://github.com/lampepfl/dotty/releases)
+
+For MacOs users, we also provide a [homebrew](https://brew.sh/) package that can be installed by
+running:
+
+```shell
+brew install lampepfl/brew/dotty
+```
+
+In case you have already installed Dotty via `brew`, you should instead update it:
+
+```shell
+brew upgrade dotty
+```
+
+## Let us know what you think!
+
+If you have questions or any sort of feedback, feel free to send us a message on our
+[Gitter channel](https://gitter.im/lampepfl/dotty). If you encounter a bug, please
+[open an issue on GitHub](https://github.com/lampepfl/dotty/issues/new).
+
+## Contributing
+
+Thank you to all the contributors who made this release possible!
+
+According to `git shortlog -sn --no-merges 0.11.0-RC1..0.12.0-RC1` these are:
+
+```
+   109  Martin Odersky
+    64  Nicolas Stucki
+    34  Martin Duhem
+    25  Allan Renucci
+    16  Guillaume Martres
+    12  Aleksander Boruch-Gruszecki
+    11  Tobias Bordenca
+    10  Miles Sabin
+    10  Liu Fengyun
+     7  Aggelos Biboudis
+     7  Jaemin Hong
+     5  Paolo G. Giarrusso
+     3  duanebester
+     3  Dotty CI
+     2  Sébastien Doeraene
+     2  Saurabh Rawat
+     2  Vlastimil Dort
+     1  tOverney
+     1  Denis Buzdalov
+     1  Hermes Espínola González
+     1  Ivan Youroff
+     1  João Pedro de Carvalho
+     1  Neeraj Jaiswal
+     1  Olivier Blanvillain
+     1  poechsel
+     1  Abel Nieto
+```
+
+If you want to get your hands dirty and contribute to Dotty, now is a good time to get involved!
+Head to our [Getting Started page for new contributors](https://dotty.epfl.ch/docs/contributing/getting-started.html),
+and have a look at some of the [good first issues](https://github.com/lampepfl/dotty/issues?q=is%3Aissue+is%3Aopen+label%3Aexp%3Anovice).
+They make perfect entry points into hacking on the compiler.
+
+We are looking forward to having you join the team of contributors.
+
+## Library authors: Join our community build
+
+Dotty now has a set of widely-used community libraries that are built against every nightly Dotty
+snapshot. Currently this includes ScalaPB, algebra, scalatest, scopt and squants.
+Join our [community build](https://github.com/lampepfl/dotty-community-build)
+to make sure that our regression suite includes your library.
+
+[Scastie]: https://scastie.scala-lang.org/?target=dotty
+
+[@odersky]: https://github.com/odersky
+[@DarkDimius]: https://github.com/DarkDimius
+[@smarter]: https://github.com/smarter
+[@felixmulder]: https://github.com/felixmulder
+[@nicolasstucki]: https://github.com/nicolasstucki
+[@liufengyun]: https://github.com/liufengyun
+[@OlivierBlanvillain]: https://github.com/OlivierBlanvillain
+[@biboudis]: https://github.com/biboudis
+[@allanrenucci]: https://github.com/allanrenucci
+[@Blaisorblade]: https://github.com/Blaisorblade
+[@Duhemm]: https://github.com/Duhemm
+[@AleksanderBG]: https://github.com/AleksanderBG
+[@milessabin]: https://github.com/milessabin