Add blog post about Scala Steward

Author: fthomas

blog/_posts/2019-07-10-announcing-scala-steward.md

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+---
+layout: blog-detail
+post-type: blog
+by: Frank S. Thomas
+title: "Keep your projects up-to-date with Scala Steward"
+---
+
+I'm excited to announce version 0.3 of [Scala Steward][scala-steward] and to introduce it
+to the Scala community! Scala Steward is a robot that helps you keep dependencies,
+sbt, and sbt plugins up-to-date by automatically creating pull requests on GitHub, GitLab,
+or Bitbucket that bump outdated version numbers.
+
+## How to use it
+
+You can use it with any public Scala project on GitHub that uses sbt simply by adding it
+to [this file][repos] and then wait for the first pull requests to come in a few hours
+later. Over 500 projects are already using this public instance of Scala Steward which
+I'm running as a free service for the whole Scala OSS ecosystem. Since Sep 9, 2018,
+when Scala Steward created [its first pull request][first_pr], it has created more than
+[11 900 pull requests][created_prs] of which over [8 300][merged_prs] are already merged!
+
+Here is a screenshot of one of Scala Steward's pull requests:
+![screenshot of a Scala Steward pull request](https://user-images.githubusercontent.com/141252/60855361-e48b4200-a1f2-11e9-8173-1a53eacffd92.png)
+
+Receiving automatic pull requests that bump versions of dependencies reduces maintenance
+if your code compiles without warnings and errors with the new version. In many cases, it
+is enough to review the changelog of the new version and to check that your automated
+tests pass before merging such pull requests. If you are adventurous, you can even let
+[Scala Steward's pull requests be merged automatically][auto-merge].
+
+[scala-steward]: https://scala-steward.org
+[repos]: https://github.com/fthomas/scala-steward/blob/master/repos.md
+[first_pr]: https://github.com/fthomas/datapackage/pull/1
+[created_prs]: https://github.com/search?o=desc&q=author%3Ascala-steward+is%3Apr&s=created&type=Issues
+[merged_prs]: https://github.com/search?o=desc&q=author%3Ascala-steward+is%3Amerged+sort%3Aupdated-desc&s=created&type=Issues
+[auto-merge]: https://github.com/fthomas/scala-steward/blob/master/docs/faq.md#how-can-scala-stewards-prs-be-merged-automatically
+
+## Running your own instance
+
+You can also run your own instance of Scala Steward for your private repositories and
+join the [companies][community] that are already doing this. Unfortunately this isn’t
+[well documented][docs-running] yet. Improving the documentation would make a great
+first contribution after you have figured out how to set it up.
+
+[community]: https://github.com/fthomas/scala-steward#community
+[docs-running]: https://github.com/fthomas/scala-steward/blob/master/docs/running.md
+
+## Automatic code migrations with Scalafix
+
+What if a new version of your dependencies contains breaking changes so that your
+code does not compile without errors or warnings anymore? In these cases automatic
+version bumps only notify you of a new version and make you aware that human
+intervention is needed to fix errors and warnings and to adapt the code to the new
+version.
+
+Fortunately, we can improve on this situation by combining Scala Steward with the
+excellent [Scalafix][scalafix] tool. Scalafix is a refactoring and linting tool that
+allows to rewrite code based on user-supplied rules. You can read more about Scalafix
+[here][scalafix-blog1] and [here][scalafix-blog2]. Scalafix rules can also be used
+for version migrations to help users updating to new versions and some
+libraries (like [Cats](https://github.com/typelevel/cats/tree/v1.6.1/scalafix),
+[FS2](https://github.com/functional-streams-for-scala/fs2/tree/v1.0.5/scalafix), or
+[http4s](https://github.com/http4s/http4s/tree/v0.20.3/scalafix)) are already
+providing such migrations. With Scala Steward, we now have the possibility to apply
+Scalafix migrations automatically to create
+[pull requests like this][scalafix-example-pr]: 
+
+```diff
+diff --git a/build.sbt b/build.sbt
+--- a/build.sbt
++++ b/build.sbt
+ libraryDependencies := List(
+-  "org.typelevel" %% "cats-core" % "0.9.0"
++  "org.typelevel" %% "cats-core" % "1.6.1"
+ )
+
+diff --git a/src/main/scala/cats_1_0_0.scala b/src/main/scala/cats.scala
+--- a/src/main/scala/cats.scala
++++ b/src/main/scala/cats.scala
+ object cats {
+-  (Option(1) |@| Option(2) |@| Option(3)).map(_ + _ + _)
++  (Option(1), Option(2), Option(3)).mapN(_ + _ + _)
+ }
+```
+
+Besides bumping the Cats version number, the Scalafix migration took care of the
+breaking changes that were introduced between Cats 0.9.0 and Cats 1.0.0 and updated
+the code so that it compiles cleanly with the new version. These automatic
+migrations have the potential to significantly reduce maintenance costs of version
+updates that contain breaking changes or deprecations.
+
+[scalafix]: https://scalacenter.github.io/scalafix/
+[scalafix-blog1]: https://www.scala-lang.org/blog/2016/10/24/scalafix.html
+[scalafix-blog2]: https://www.scala-lang.org/blog/2018/11/16/scalafix-scalameta.html
+[scalafix-example-pr]: https://github.com/fthomas/scalafix-test/pull/9/files
+
+## Get involved
+
+Scalafix migrations are great but we haven't yet solved the problem of writing them
+automatically for version updates. **:-)** That means there are plenty of opportunities
+for new contributors to help library maintainers writing Scalafix migrations. And by
+integrating them into Scala Steward, their value is amplified by the number of
+projects that use Scala Steward. Even small contributions can already benefit a
+large chunk of the Scala ecosystem.
+
+After you have written a Scalafix migration for your favorite library,
+Scala Steward needs to be made aware that it exists and for which version update it
+should be applied. Instructions for adding them to Scala Steward and more details about
+the Scalafix integration in Scala Steward can be found [here][scalafix-migrations].
+Once the migration has been added and the new version of the library is released, you
+can enjoy watching Scala Steward creating pull requests with changes from your Scalafix
+migration!
+
+There are also enough opportunities to [improve Scala Steward itself][scala-steward-issues].
+The Scalafix integration, for example, has only been added recently and is still rough around
+the edges.
+
+[scalafix-migrations]: https://github.com/fthomas/scala-steward/blob/master/docs/scalafix-migrations.md
+[scala-steward-issues]: https://github.com/fthomas/scala-steward/issues
+[scala-steward-contributors]: https://github.com/fthomas/scala-steward#contributors
+
+## Recap
+
+Scala Steward: 
+
+* Can create automatic pull requests that bump dependency versions. This saves a lot of time.
+* In addition to the version bumps, it can migrate the code with Scalafix.
+* You can help the whole Scala ecosystem by writing Scalafix migrations.
+
+[Try out Scala Steward][quickstart] now!
+
+[quickstart]: https://github.com/fthomas/scala-steward#quick-start-guide
+
+## Credits
+
+Scala Steward wouldn't exist without Roman Timushev's great [sbt-updates][sbt-updates]
+which is an integral part of Scala Steward. A special shout-out also goes to
+[@impurepics][@impurepics] who created the cute and iconic logo!
+
+And many thanks to the 20+ contributors who made Scala Steward to what it is today:
+Alex,
+Arulselvan Madhavan,
+Bayram Kiran,
+Cédric Chantepie,
+Christopher Davenport,
+Dale Wijnand,
+Daniel Pfeiffer,
+David Francoeur,
+Fabian,
+Filipe Regadas,
+Jakub Kozłowski,
+JCollier,
+Jeff Martin,
+kenji yoshida,
+Mark Canlas,
+Michael Wizner,
+Philippus Baalman,
+Piotr Gabara,
+Renato Cavalcanti,
+sullis,
+TATSUNO Yasuhiro,
+Thomas Heslin, and
+Thomas Kaliakos.
+
+I'd also like to thank Andrea Magnorsky, David Francoeur, Lars Hupel,
+Seth Tisue, and Yifan Xing for proofreading this post.
+
+[sbt-updates]: https://github.com/rtimush/sbt-updates
+[@impurepics]: https://twitter.com/impurepics/