Add Scala Center roadmap for 2023

blog/_posts/2023-01-24-scala-center-2023-roadmap.md

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+---
+layout: blog-detail
+post-type: blog
+by: the Scala Center team
+title: Scala Center Roadmap for 2023 and Beyond
+description: Highlights of the achievements of the Scala Center in 2022, and roadmap for 2023.
+---
+
+In this post, we summarize the achievements of the Scala Center in 2022, and share our plans going forward to
+ensure the longevity of Scala.
+
+## Role of the Scala Center in the Scala Ecosystem
+
+Overall, the mission of the Scala Center is to **improve the experience of becoming and being a Scala developer**, and
+to **help the community to build a rich ecosystem of libraries**.
+
+The Scala ecosystem is made of the following pillars:
+
+- **Language, compiler, standard library:** they are the core tools that all programmers interact with when they
+  work in Scala. The role of the Scala Center is to reduce the number of bugs in the compiler implementation, to help
+  the community to contribute to these tools, and to make sure they evolve in a way that takes into account the needs
+  of the community.
+- **Documentation and MOOCs:** this website is the entry point to the ecosystem. It showcases the strengths of the
+  language and its use-cases, and it hosts all its documentation. The role of the Scala Center is to simplify the
+  structure and the content of the website, to create and maintain high-quality online educational content (including
+  online courses), and to help the community to contribute to the website.
+- **Developer experience:** Scala programmers often don’t interact directly with the compiler, but they use a tool
+  (build tool, compiler server) that does that for them. They also use tools to edit, analyze, navigate through,
+  transform, compile, run, and debug Scala programs. The role of the Scala Center is to make sure these tools are as
+  easy to use as possible, that they work reliably for everyone, and deliver a great developer experience.
+- **Community and contributor experience:** the last pillar is the result of the work done _outside_ the Scala Center.
+  The community has created thousands of projects that bring simple solutions to complex problems. The role of the
+  Scala Center is to create the best environment for the emergence of such libraries.
+
+The remainder of this article summarizes our achievements in those four areas in 2022, and then presents our goals
+going forward.
+
+## Highlights of 2022
+
+In this section, we highlight our main achievements in 2022. You can find our complete activity reports on
+[our website](https://scala.epfl.ch/records.html).
+
+### Language, Compiler, Standard Library
+
+**We overhauled and restarted the [Scala Improvement Process](https://docs.scala-lang.org/sips/).** Since last
+summer, the diverse members of SIP Committee meet monthly to decide the evolution of the language. As we explained
+in the [announcement]({% link blog/_posts/2022-07-13-scala-improvement-process-reloaded.md %}), the main changes of
+the new process are the following. First, the proposals are thoroughly discussed by a team of three reviewers, publicly
+on [GitHub](https://github.com/scala/improvement-proposals) before the whole Committee votes on them during their
+monthly meetings. Second, there is a new stage where proposals are accepted as experimental features before the Committee
+votes again to promote them to stable features.
+
+**We improved [generic Mirror](https://docs.scala-lang.org/scala3/reference/contextual/derivation.html#mirror) synthesis.**
+Mirrors are critical to metaprogramming in Scala 3, they enable implementation of type class derivation without
+advanced metaprogramming techniques such as macros. Mirror synthesis now supports more cases
+([generic tuples](https://github.com/lampepfl/dotty/pull/15250),
+[local and inner classes](https://github.com/lampepfl/dotty/pull/15847)), is more reliable
+([dotty#15279](https://github.com/lampepfl/dotty/pull/15279),
+[dotty#15404](https://github.com/lampepfl/dotty/pull/15404),
+[dotty#15814](https://github.com/lampepfl/dotty/pull/15814)), and provides
+[more detailed explanations in case of failure](https://github.com/lampepfl/dotty/pull/15164).
+
+**We generalized the definition of methods in Scala** by allowing type parameters to be interleaved with regular parameters.
+This change notably allows methods to take type parameters whose bounds depend on value parameters. You can learn more
+about the motivation behind this change in the proposal document:
+[SIP-47 - Clause Interleaving](https://docs.scala-lang.org/sips/clause-interleaving.html). Last, we lifted a current
+language restriction that prevents eta-expansion to be applied to polymorphic methods. You can learn more about this
+change in the proposal document:
+[SIP-49 - Polymorphic Eta-Expansion](https://docs.scala-lang.org/sips/polymorphic-eta-expansion.html). Both proposals
+have been accepted by the SIP Committee and are under development in the compiler.
+
+### Documentation and MOOCs
+
+**We improved the usability of the Scala website (this website).** The website had not seen a major rework since 2013,
+and it does not represent the full picture that we would like Scala newcomers to see. To this effect, we have removed
+the split of Scala 2 vs Scala 3 on [the landing page](https://github.com/scala/scala-lang/pull/1344) and on
+[the documentation](https://github.com/scala/docs.scala-lang/pull/2430), consolidated the “Getting Started” instructions
+([scala-lang#1344](https://github.com/scala/scala-lang/pull/1344),
+[scala-lang#1348](https://github.com/scala/scala-lang/pull/1348),
+[scala-lang#1352](https://github.com/scala/scala-lang/pull/1352),
+[scala-lang#1373](https://github.com/scala/scala-lang/pull/1373),
+[docs.scala-lang#2388](https://github.com/scala/docs.scala-lang/pull/2388),
+[docs.scala-lang#2520](https://github.com/scala/docs.scala-lang/pull/2520)), improved the
+[contributing guide](https://github.com/scala/docs.scala-lang/pull/2350), and created an infrastructure to show both
+Scala 2 and Scala 3 versions of code examples in the documentation
+([docs.scala-lang#2450](https://github.com/scala/docs.scala-lang/pull/2450)). We created an
+[issue](https://github.com/scala/docs.scala-lang/issues/2481) to coordinate the update of the whole documentation to
+always show both Scala 2 and Scala 3 code examples when possible.
+
+**We offered individualized support to our MOOCs’ learners.** We published the course “Effective Programming in Scala”
+to the [Extension School platform](https://www.extensionschool.ch/learn/effective-programming-in-scala). This
+platform allows the learners to have regular 1-on-1 meetings with our instructors along their learning journey. Learn
+more about the motivation in the previous [announcement]({% link blog/_posts/2022-06-08-learn-scala-at-epfl-extension-school.md %}).
+
+### Developer Experience
+
+**We improved the debugger for Scala 3.** The Metals’ debugger is now able to evaluate arbitrary Scala 3 expressions
+while the debugger is paused in the middle of a program. Step-by-step execution now automatically skips the methods
+generated by the compiler (e.g. mix-in forwarders, getters, setters, bridge methods, and synthetic methods of case
+classes). Learn more in [this video](https://www.youtube.com/watch?v=UePrOa_1Am8).
+
+**We fixed the apps installed by the [setup instructions](https://docs.scala-lang.org/getting-started).** The
+command-line apps `sbt` and `scala` now behave consistently regardless of the installation process (`cs install` vs
+manual download of the release artifacts).
+
+### Community and Contributor Experience
+
+**We co-organized the [ScalaCon](http://www.scalacon.org/) online conference.** We were in charge of the program and
+the program committee.
+
+**We published videos about Scala 3.** [Let’s Talk About Scala 3](https://www.youtube.com/playlist?list=PLTx-VKTe8yLxYQfX_eGHCxaTuWvvG28Ml)
+is a series of videos where we share interesting, useful, and cool things related to Scala 3. We published 4 new
+videos in 2022.
+
+**We improved the code editing experience in [Scastie](https://scastie.scala-lang.org).** Scastie is the online Scala
+code editor that is used every day by one thousand developers to share code snippets in the community. We have 
+implemented “IDE features” such as autocompletion and showing type information under the mouse pointer.
+
+**We mentored new contributors to the Scala 3 compiler.** Diving into the compiler is not an easy task. The Compiler
+Academy organizes online pair-programming events to mentor new contributors on the compiler codebase. You can learn
+more about the Compiler Academy in [this blog article]({% link blog/_posts/2022-11-02-compiler-academy.md %}).
+
+**We implemented the building blocks of a new tool to detect incompatibilities between programs.** Guaranteeing the
+absence of incompatibilities between library dependencies is the cornerstone of a peaceful Scala ecosystem. We have
+implemented a prototype of a new tool to detect incompatibilities between two versions of a program (like
+[MiMa](https://github.com/lightbend/mima), but based on the TASTy representation of programs instead of JVM bytecode).
+Our work is based on [TASTy Query](https://github.com/scalacenter/tasty-query), which will be the basis of tools to
+perform static analysis of Scala programs (it is already used by the Metals debugger).
+
+## Roadmap for 2023 (and Beyond)
+
+It is now time to look forward and present our goals for 2023. Our mission remains the same: improve the experience of
+becoming and being a Scala developer, and help the community to build a rich ecosystem of libraries. Ultimately, our
+work will ensure the longevity of Scala by creating a reliable and resilient ecosystem.
+
+We have identified the priorities for 2023 through our discussions with the community (online or at conferences),
+with our [Advisory Board members](https://scala.epfl.ch/#advisory-board-member-list), and with the
+main organizations that are [behind Scala](https://www.scala-lang.org/community/#whos-behind-scala)
+([LAMP](https://lamp.epfl.ch), [Lightbend](https://lightbend.com), and [VirtusLab](https://virtuslab.com)). We are
+grateful to all of them.
+
+In the following subsections we remind our ongoing and recurring projects, and we present our most important goals as
+well as some additional stretch goals that would need more resources.
+
+The roadmap we present here is of course subject to adjustments throughout the year.
+
+### Language, Compiler, Standard Library
+
+In addition to keeping the Scala Improvement Process going, and reducing the number of bugs in the compiler and standard
+library, we will:
+
+- **Make the compiler error messages clearer and more actionable.** The compiler should help developers write correct code
+  instead of “just complaining” about incorrect code. The compiler should also guide you to write maintainable code (ie,
+  it should provide linting features). You can find a list of related issues
+  [here](https://github.com/lampepfl/dotty/issues?q=is%3Aopen+is%3Aissue+label%3Aarea%3Areporting).
+- **Bring the compiler’s suggestions into the IDEs.** Instead of emitting only text output, the compiler
+  will produce structured output that IDEs (Metals and IntelliJ) will be able to read to automatically provide “quick
+  fixes” to the users. This should reduce the implementation (and maintenance) costs on the IDE side.
+- **Unfreeze the Scala standard library.** The standard library has not changed (except for bug fixes or some performance
+  improvements) since Scala 2.13, which was released almost four years ago. [Dropping the forwards binary compatibility
+  requirement](https://github.com/scala/improvement-proposals/pull/54) would be a first step to allow the introduction
+  of new classes or the addition of new members to the existing classes. Then, we will create a process to validate
+  what should be in the standard library and what should stay outside of it.
+- **Clarify and communicate the Scala 3 roadmap.** We will coordinate with the compiler team to clarify what will
+  go into the [Long-Term Support version]({% link blog/_posts/2022-08-17-long-term-compatibility-plans.md %})
+  of Scala 3, and make sure that roadmap is well communicated. We will focus primarily on the items that will
+  enable more users to migrate from Scala 2 to Scala 3 (e.g., missing compiler options).
+
+Our stretch goals include: publish a formal specification for Scala 3, investigate opportunities for reducing
+compilation times, implement multi-threading in Scala Native, and remove the dependency to the Google Closure
+Compiler in Scala.js.
+
+### Documentation and MOOCs
+
+In addition to maintaining the Scala website and managing our online course learners, we will:
+
+- **Add “task-oriented” content to the documentation.** Currently, the documentation is rather “language features oriented”,
+  but it does not really help solve concrete problems. We will select a set of libraries (the “Scala Toolkit”) and we
+  will write tutorials showing how to perform common programming tasks (working with JSON, writing tests, etc.).
+  We will use libraries created by the community and that do not require advanced knowledge of Scala. Last, we will
+  help the authors of those libraries to perform the usual maintenance tasks.
+- **Improve the content of the course
+  [Effective Programming in Scala](https://docs.scala-lang.org/online-courses.html#effective-programming-in-scala).**
+  We will address the feedback we received from the learners of the course to smoothen the learning curve.
+
+Our stretch goals include: update our [Spark course](https://docs.scala-lang.org/online-courses.html#scala-specialization),
+teach Scala to first year Bachelor students at EPFL, and create a new Scala course for beginners (with no experience at
+all in programming).
+
+### Developer Experience
+
+In addition to maintaining some core tools of the ecosystem (Bloop, Coursier, sbt, scala-debug-adapter), we will:
+
+- **Streamline the distribution of `cs` (Coursier).** The current setup process is not well integrated with the various
+  operating systems. There are no packages for Linux distributions, no MSI installer for Windows, and no PKG or DMG
+  installer for macOS.
+- **Reduce the number of ways to import Scala projects in IDEs.** Currently, IDEs support several ways for importing
+  Scala projects (via sbt or via a build server, which itself can be provided by bloop or the underlying build tool).
+  This is a source of confusion for the users, and it increases the maintenance costs.
+- **Make Metals work with more versions of Scala.** By creating a stable interface for the presentation compiler,
+  Metals will be less tied to the release cycles of the compiler, and it will easier to use it to develop the
+  compiler itself.
+- **Improve the Scala 3 support on Metals and IntelliJ.** We heard many developers stating that the Scala 3 support
+  in IDEs was not at the same level as Scala 2, and that is one of the blockers to migrate to Scala 3. We will
+  identify and put weigh on the main issues that currently degrade the developer experience on Scala 3 projects.
+
+Our stretch goals include: support standalone .scala files out of the box in Metals and IntelliJ (including support
+for Scala CLI configuration directives), investigate opportunities to reduce build times, reduce the maintenance costs
+of implementing the `debugSession/start` endpoint in all the build servers by running the debug server in Metals,
+update scalameta to Scala 3, publishing sbt 2, implement a Scala 2 expression evaluator in scala-debug-adapter,
+be able to choose a specific build target in Metals, make sure Scala programs are easy to deploy especially in IaaS,
+and provide TASTy trees to semantic rules in Scalafix.
+
+### Community and Contributor Experience
+
+In addition to continuing co-organizing ScalaDays, participating to conferences, publishing positive content about
+Scala, leading the Compiler Academy, and maintaining tools for contributors ([Scastie](https://scastie.scala-lang.org),
+[Scaladex](https://index.scala-lang.org), [scalafix](https://scalacenter.github.io/scalafix/)), we will:
+
+- **Add support for standalone Scala programs in Scastie.** Currently, Scastie creates an sbt project for every snippet.
+  This adds a performance overhead, and makes it impossible to just copy-paste a snippet to run it locally (because
+  you also need to re-create the sbt configuration locally). We will fix this issue by supporting a “standalone” mode
+  where the configuration will be defined via Scala CLI directives.
+- **Publish TASTy-MiMa.** This tool will be able to detect incompatibilities between two versions of a program, based
+  on their TASTy representation. We will complete its implementation and make it available to the community.
+- **Streamline the way to publish the documentation of Scala libraries.** Currently, there are many tools one can use
+  to publish documentation about their open-source projects (Scaladoc, Paradox, Laika, Docusaurus, etc.). Developers
+  should not have to study or experiment with many tools to produce the documentation they need. We will simplify how
+  to produce API documentation, how to “typecheck” the code examples, how to keep multiple versions of the documentation
+  online, and how to define custom “template directives” in Scala.
+
+Our stretch goals include: coordinate Google Summer of Code, create a Scala Center online shop, stabilize and document
+the HTTP API of Scaladex, make it easy to find projects to contribute to in Scaladex, implement GitHub [precise code
+navigation](https://docs.github.com/en/repositories/working-with-files/using-files/navigating-code-on-github#precise-and-search-based-navigation)
+for Scala, and simplify the usage of remote caching techniques in continuous integration systems.
+
+## Conclusion
+
+In this article, we have looked at the pillars of the Scala ecosystem, and for each of them we have listed the main
+outcome of our work in 2022, and our main goals for 2023.
+
+Achieving these goals is possible only with your [support](https://scala.epfl.ch/faqs.html) and with the help of all
+the [people behind Scala](https://www.scala-lang.org/community/#whos-behind-scala). Thank you all!
+
+You can find our detailed roadmap for the current quarter [here](https://scala.epfl.ch/projects.html),
+and track our progress by looking at our [quarterly reports](https://scala.epfl.ch/records.html), or by browsing the
+[Scala Center Updates](https://contributors.scala-lang.org/c/scala-center/25) category of the Scala Contributors forum.