A free, once-weekly Scala news flash. Easy to unsubscribe. Goes out every Thursday.
March 15th, 2018, ISSUE 213


Generic Programming and Shapeless with Miles Sabin

A new episode of the CoRecursive w/ Adam Bell podcast.
Miles Sabin, Adam Bell (@milessabin)
Implementing an event-driven HTTP server with Scala Native

In this post I'm going to introduce Scala Native by using it to write a simple HTTP server using a C library called libuv.
Chris Birchall (@cbirchall)
Survey on Swagger with Akka HTTP

TL;DR) You can use Swagger with Akka HTTP and get some benefit from Swagger, but the workflow is not fully automated with existing tools.
Richard Imaoka (@richardimaoka)
AST-free JSON parsing

Provisional benchmarks of AST-free serialization puts my WIP branch of uPickle about ~40% faster than circe on my current set of ad-hoc benchmarks, if the encoders/decoders are cached.
Li Haoyi (@li_haoyi)
5 steps of creating your very first Type Class in Scala

In this blog post you will learn about how to implement your first type class, which is fundamental language feature in the icon of the functional programming languages — Haskell.
Adam Gajek (@adam_gajek)
Scala: try-with-resources

Despite the fact that resource management is a well-known subject, there are still many mistakes around it.
Dmitry Komanov (@dkomanov)
Avoid pattern matching with List in Scala

recently debugged a strange issue which seemed to appear out of nowhere™. It all came down to a that we used List in a match while the methods signature was changed from List to Seq.
Anton Fagerberg (@AntonFagerberg)
Understanding Functor and Monad With a Bag of Peanuts

When I started coded in Scala I heard someone saying List, Option, Future etc. are all monads and functors. I wanted to understand what exactly is a monad or a functor.
Sujit Kamthe (@sujeet100)
Announcing discuss.akka.io!

We’re pleased to announce a new way to communicate with the core team and communities around the Akka projects (including Akka HTTP, Alpakka the various persistence plugins and all other community projects), as well as downstream projects such as Play and Lagom.
Akka Team
Deploying a Medical Time Series Model using Zeppelin Notebooks and SKIL

One of the largest barriers to deriving value from machine learning (ML) in clinical and other enterprise settings is the handoff from data science to production deployment. We have shown how SKIL provides a single environment in which to create, analyze, and deploy models for production quickly and easily, easing this handoff.
Briton Park


ScalaUA, April 20-21, 2018, Kyiv, Ukraine

Use promo code "ScalaTimes_ScalaUA-2018-20-04" for 5% discount!
Scala Sphere, April 15-17, Kraków, Poland

Use promo code sphereit-2018-scalatimes for 10% discount for Scala Times readers!
Scala Sphere (@ScalaSphere)
Scalapeño 2018 CFP, July 2, Beer Sheva, Israel

Send your proposal before 2018.04.01.
Blockyard Conference, April 13, Gdańsk, Poland

Use our promo link to get a 40% discount for Scala Times readers!


akka-http-json 1.20.0

akka-http-json provides JSON (un)marshalling support for Akka HTTP via Argonaut, circe, Jackson, Json4s, Play JSON, uPickle, and avro4s.
akka-http-json contributors

Idiomatic, typesafe, and reactive Scala client for Apache Pulsar
Stephen Samuel

This is an sbt plugin that aims to lower the latency between file system events and sbt tasks. It replaces the default watch service with a more highly optimized service that works well on all platforms.
Ethan Atkins
scalajs-react 1.2.0

React 16 support and adherence, new shapes, type-safe and purely-functional AJAX + much more.
scalajs-react contributors

A simple framework for creating embedded DSL in Scala control flow.
Yang Bo
kafka-streams-scala 0.2.0

This release brings implicit Serdes, more typesafety, misc refactorings.
Akka HTTP 10.1.0

The new client pool implementation introduced in 10.0.11 is now the default, Experimental artifacts are available for Scala 2.13.0-M3, no more Akka 2.4.x support, and much more updates.
akka-http contributors
Dotty 0.6.0 and 0.7.0-RC1

These releases serve as a technology preview that demonstrates new language features and the compiler supporting them.
Dotty contributors
Travesty 0.9

A library for generating structural diagrams of your Akka Streams. First of all, supported Akka versions have been extended up to 2.5.11. Most importantly, Travesty can now generate diagrams from any graph, not only RunnableGraph / Graph[ClosedShape].
Mikołaj Koziarkiewicz (@mikolak_net)


Scala Times banners?

Want one? Click here
Scala Times stickers?

Want one? Let us know or tweet @scalatimes.

  1. Scala Times Issue #234

    Reverse State Monad in Scala. Is it possible?. Typedapi or how to derive your clients and servers from types. Testing in the wild. Akka HTTP request/response scope operations, vs. Deferred operations. Akka anti-patterns: too many actors.

  2. Scala Times Issue #233

    Akka HTTP and TCP streaming. Play Framework Action Composition. Scala 3 as a new Programming Language. [SPARK-14220] Build and test Spark against Scala 2.12 - ASF JIRA. How Curalate uses MXNet on AWS for some Deep Learning Magic.

  3. Scala Times Issue #232

    Akka anti-patterns: Java serialization. Practical Cats: Functor and Applicative. Why Scala Implicits. Implicits, type classes, and extension methods, part 4: understanding implicits. Scala FUD FAQ for newbies.

  4. Scala Times Issue #231

    Can someone explain to me the benefits of IO? . Shared State in Functional Programming. Demystifying Dependency Injection with Airframe. Scala Wars: FP-OOP vs FP. Lambda World Seattle, September 17th - 18th .

  5. Scala Times Issue #232

    Can someone explain to me the benefits of IO? . Shared State in Functional Programming. Demystifying Dependency Injection with Airframe. Scala Wars: FP-OOP vs FP. Lambda World Seattle, September 17th - 18th .

  6. Scala Times Issue #230

    Teaching Evolution With Genetic Algorithms. Rolling Your Own Monad To Deal With Nested Monads In Scala. Case Study - Solve Crosswords Puzzle. Scala Type Level – Part 4 : Way to the HigherKinds. Implicits, type classes, and extension methods, part 2: implicit derivation.

  7. Scala Times Issue #229

    How to turn ugly Java APIs into elegant, type-safe Scala APIs. Analyzing Pwned Passwords with Apache Spark. Understanding Parametricity in Scala. Are Scala Streams really lazy?. Convolutional LSTM for ocean temperature with Deeplearning4j.

  8. Scala Times Issue #228

    Compiling Scala Faster with GraalVM. Scala Compiler Options. Scalable read model updates in Akka Persistence. Are there exceptions in Scala?. Lambda World Seattle, September 17th - 18th .

  9. Scala Times Issue #227

    Compilation safety on Playframework’s i18n with Scala Macros. Reflections on using Typelevel Scala. A simple way to write parsers: using the State monad. Writing a simple Telegram bot with tagless final, http4s and fs2. Lambda World Seattle, September 17th - 18th .

  10. Scala Times Issue #226

    Scala in 2018 - The State of Developer Ecosystem by JetBrains. Combining ScalaCheck generators. Scalaz 8 IO vs Akka (typed) actors vs Monix (part 1). Use the decorator pattern for clean I/O boundaries. Scala - AnyVal meets Pattern Matching.

  11. Scala Times Issue #225

    Speeding Up Compilation Time with `scalac-profiling`. Partitioning Akka Streams for Scalability and High-Availability. Bringing back power assert with Expecty. Hot source dependencies using sbt-sriracha. Running akka-cluster on Kubernetes.

  12. Scala Times Issue #224

    Incorporating FaceNet into Play framework with Silhouette authentication. Futures in Scala Protips (part 5): Try more. Zero-Overhead Tree Processing with the Visitor Pattern. More Readable Code in Scala. Relearn your sbt.

  13. Scala Times Issue #223

    Open Offer: Pair program with me. How well do you know your Akka trivia?. ScalaDays 2018 Berlin Takeaways. Scalar 2018 whiteboard voting results!. Implicit Implications (part 1): Implicit Parameters.

  14. Scala Times Issue #222

    Product with Serializable. Scala Enumerations hell. Running Play on GraalVM. Tagless Final algebras and Streaming. 10 Reasons to Learn Scala and FP - DZone Java.

  15. Scala Times Issue #221

    Akka Typed: Hello World in the new API. No More Transformers: High-Performance Effects in Scalaz 8. Writing Internal DSL in Scala. On Bifunctor IO and Java's Checked Exceptions. Partitioning Akka Streams to Maximize Throughput.

  16. Scala Times Issue #220

    Better logging with Monix 3, part 1: MDC. Learning how to code with Scala: Hello, World!. Responding to Incoming Text Messages with Scala and Finatra. Understanding F[_] in Scala. Macros: the Plan for Scala 3.

  17. Scala Times Issue #219

    A quick tour of build tools in Scala. Towards Scala 3. CoRecursive: Graphql And Sangria. Using Redux with Binding.scala. Testing Play Framework with H2 in-memory database.

  18. Scala Times Issue #218

    Cats: Safe Resource Acquisition and Release. An ode to the kind-projector and to the partial-unification of Scala. Models of Computation - Part 2 - How? (inspired by SICP). ScalaUA, April 20-21, 2018, Kyiv, Ukraine. WIN a ticket to Scala Days Berlin!.

  19. Scala Times Issue #217

    A Functional Interface for Key/Value Store. Defeat your 99th percentile with speculative task. Synchronous or asynchronous, and why wrestle with wrappers?. Running Spark on a Cluster: The Basics. Talks from Scalar Conference 2018.

  20. Scala Times Issue #216

    Boilerplate free testing with Scalacheck and Magnolia. ScalaUA, April 20-21, 2018, Kyiv, Ukraine. Scala Sphere, April 15-17, Kraków, Poland. Blockyard Conference, April 13, Gdańsk, Poland. Scala Native 0.3.7.

  21. Scala Times Issue #215

    Akka anti-patterns: overusing ActorSelection. Twilio guardrail: Principled Code-Generation for Type-Safe Languages. Google Summer of Code 2018 Scala Projects. Sequential Traverse for managing parallel resource usage in Scala. Dependency Inversion | Inversion of Control (IoC) For Absolute Beginners.

  22. Scala Times Issue #214

    Cats Effect: IO. Stepping down as the maintainer of scalamacros/paradise. Accessibility of the Scala Compiler. IO Monad and Monad Transformers for Rookies. Exploring Type Annotations in Scala.

  23. Scala Times Issue #213

    Generic Programming and Shapeless with Miles Sabin. Implementing an event-driven HTTP server with Scala Native. Survey on Swagger with Akka HTTP. AST-free JSON parsing. 5 steps of creating your very first Type Class in Scala.

  24. Scala Times Issue #212

    Scala-view: Animate streams of images. Creating forms on your Play application - Part 2. Typesafe Union-type folding in Scala. ManagedT: Compositional resource management. NeoVim + Scala.

  25. Scala Times Issue #211

    Top 15 Scala Libraries for Data Science in 2018. Static Sorting in Slick. Safe(r) mappings in Slick with Shapeless. Tour of Akka Cluster - Cluster Sharding. Akka cluster on kubernetes. Traps and pitfalls.

Organizing an event?
Promote it with
Scala Times.
The Scala Times reader?
Get a banner!
Got a tip? Send it in!
Follow us on Twitter.
Curated by SoftwareMill.
We are hiring.
And taking on projects.