A free, once-weekly Scala news flash. Easy to unsubscribe. Goes out every Thursday.
January 2nd, 2020, ISSUE 307


Standardizing IO Interfaces for Scala Libraries

Exploration of two interfaces: Writable and Readable - the new standard of Li's OSS.
Li Haoyi (@li_haoyi)
WebSocket Streaming with Scala

How Akka Streams can make life easier.
Duane Bester (@duanebester)
State of Monocle

An experiment with various optics encoding: pair of functions, Van Laarhoven, and profunctor (see LensImpl).
Julien Truffaut (@JulienTruffaut)
Scala tooling in 2019

The highlight of a few of the developments from 2019.
Ólafur Páll Geirsson (@olafurpg)
How to Work with Scala Collections in Java

The short tutorial for Java developers who want to use Scala libraries and need to work with Scala collections.
Uri Bechar
Write Clean and SOLID Scala Spark Jobs

A guide to writing extensible and maintainable Spark jobs that increase the data team’s productivity and guarantee better products.
Ronald Ángel
Currying in Scala: A Useful Example

The usage of the functionality in a programming language.
Kadir Malak
Generic Traits and Classes With Type Parameters And Variance

The exploration of variance.
Knoldus Inc. (@Knolspeak)
Operator overloading in Scala and Kotlin: two slightly different ways

If Scala has a feature, Kotlin probably has that same feature too, right?
Alonso Del Arte
How to use the same Test for different Implementations with ZIO

I think ZIO gives me (as a simple Programmer without Ph.D.) the chance to get to my next level of Functional Programming.
Mocking The Right Way

Using Mockito requires changing how we think about unit tests while removing a lot of boilerplate.
Knoldus Inc.
SPNEGO Token generation

SPNEGO - is a simple and protected negotiation mechanism used by client-server software.
Alexey Novakov (@alexey_novakov)
SBT for the absolute beginner 1 (Basics and dependency Management)

SBT also has its own interactive shell that is run by just calling sbt, commands like run, clean and test can then be directly entered into the shell.
Orji Samuel


Using Tagless Final with laws - Scala tutorial

In this video, you'll learn about the Tagless Final technique and a way to correctly implement and test a Tagless Final algebra in your program.
Jakub Kozłowski (@kubukoz)


Lambda Days, February 13th -14th 2020, Kraków, Poland

Draft paper submission by January 13th.
Lambda Days (@LambdaDays)
ScalaUA, April 3th-4th, 2020 Kyiv, Ukraine

CFP is on! Wholesale 10+ tickets are available till 2020.04.02.
ScalaUA (@ScalaUA_Conf)
Scalar, March 19th-21st, 2020, Warsaw, Poland

Get ready for one of the biggest Scala conferences in Europe!
SoftwareMill (@scalarconf)



A small library to encode event-sourcing patterns using FS2, a streaming library in Scala.
Ryan Peters (@LiquidSloshalot)

An ONNX (Open Neural Network eXchange) API, Code Generator and Backend for Typeful, Numerically Generic, Functional Deep Learning in Scala.
Alex Merritt


Scala Times banners?

Want one? Click here
Scala Times stickers?

Want one? Let us know or tweet @scalatimes.
Scala experts?

Need some? SoftwareMill is here, ready to talk and dive deep into your code.

  1. Scala Times Issue #327

    Time traveling in tests with Cats Effect. Lightbend To Contribute Commercial Features To Akka Open Source. Functional error handling with monads, monad transformers and Cats MTL. Akka Stream Coexistence With Akka Typed. Orchestrating startup and shutdown in Scala.

  2. Scala Times Issue #326

    A story about streaming unique batches in Monix. GraalVM Native Image Tips & Tricks. Mu-Scala 0.22: Distributed tracing. Using a remote server to build your Scala projects. Circe - Part 2 - JSON Codecs.

  3. Scala Times Issue #325

    Scala Start Page. Starting with Scala 3 macros: a short tutorial. Implementing Authentication on Play Framework. Lunatech and our commitment to the Scala Center. Scala Native Next Steps.

  4. Scala Times Issue #324

    A simple trick to improve type safety of your Scala code. The Power of Akka Streams. Akka Persistence JDBC 4.0.0 release candidate. Scala Book: Free PDF, Mobi, and ePub versions. Testing Embedded H2 DB with Scala and Scalatest.

  5. Scala Times Issue #323

    ZIO + Http4s: a simple API client. FP for Mortals for Cats!. An Introduction to ZIO Kafka. Akka Typed Fundamentals (PL), Online Workshop, April 27th. Scalar Online, May 15th (Extended CFP).

  6. Scala Times Issue #322

    The Death of Hype: What's Next for Scala. IntelliJ Scala Plugin 2020.1. Data processing with Akka Actors: Part II. Akka-http graceful shutdown. A Brief History of ZIO.

  7. Scala Times Issue #321

    Tapir codecs get an update. Data processing with Akka Actors: Part I. A functional comparer. Data Juggling - Part 11 - Getting Started with Squants. Scalar Online, May 15th (CFP).

  8. Scala Times Issue #320

    New feature: Search!. Bake your bread tagless-final style. User-land compiler warnings in Scala. Zio ZLayer with playframework. Testing background process with ZIO.

  9. Scala Times Issue #319

    From idea to product with ZLayer. Edge to Cloud: Building the Tesla Virtual Power Plant . What's the Point of Applicative?. Using ScalaCheck with MUnit. Monitoring and tracing for Akka applications under kubernetes (k8s).

  10. Scala Times Issue #318

    Akka Cluster application design. Spring to ZIO 101. NE Scala in the Time of Social Distancing. Scala 3 support in IntelliJ Scala plugin. Separate Docker Layers for Dependencies and App JARs.

  11. Scala Times Issue #317

    Using Google Datastore with akka-persistence. Functional Program (Re)Design. Writing native CLI applications in Scala with GraalVM. Data Juggling - Part 8 - Getting Started with refined. Fundamentals of Scala, March 14th-15th, Lagos, Nigeria.

  12. Scala Times Issue #316

    How to publish a Scala library in GitHub. Announcing Cats STM 0.7.0. Baking Peixinhos da Horta with ING’s Baker Library. Fundamentals of Scala, March 14th-15th, Lagos, Nigeria. Stairway to Scala Workshop, March 16th-20th, San Damiano, CA, USA.

  13. Scala Times Issue #315

    ZIO for IntelliJ. Scala 2 community build reaches goals. Cats Effect Ref. Using Dotty Union types with Akka Typed – Part II. Caliban Client: a type-safe GraphQL Client for Scala and Scala.js.

  14. Scala Times Issue #314

    Using Dotty Union types with Akka Typed. My FP Journey. Creating a dead simple CountDownLatch with ZIO. ZIO STM: CountDownLatch in two lines. 2019 Scala Developer Survey.

  15. Scala Times Issue #313

    Building Serverless Scala Services with GraalVM. Alpakka Kafka 2.0 Released | @lightbend. Haskell for impatient Scala developer: Getting into speed. Building useful Scalacheck Generators. Easily create New Sync Types with ZIO STM.

  16. Scala Times Issue #312

    Happy eyeballs algorithm using ZIO. How (not) to use shapeless for cross-layer conversions in Scala. So you want to compose some functions. RESTful error handling with Akka HTTP and the library “endpoints”. MUnit is a new Scala testing library · MUnit.

  17. Scala Times Issue #311

    Introducing error reporting in optics. GraphQL in Scala with Caliban - Part 1. Tidying up your SBT file with Scala. Dependency injection with Reader Monad in Scala. Etcd watch API integration with scala and cats-effect.

  18. Scala Times Top Links of 2019

    January: Scala Best Practices. February: Is your Scala object always a singleton?. April: Did Functional Programming get it wrong?. May: The little gems of Scala standard library. June: The Evolution of a Scala Programmer.

  19. Scala Times Issue #310

    Git hooks in Scala projects  - the easy way!. Testing Doobie programs. Implementing typeclasses in Scala I. Effective testing with ZIO Test. Akka Streams: error handling in event processing pipelines.

  20. Scala Times Issue #309

    Towards more functional Play — Part 2. TMWL’ Dec 19 — Scala 3 overview, Scala hacks and DevOps hints. Scala etcd client with etcd4s and cats-effects. Boilerplate-free type class definition. GCP Cloud Functions with Scala.js in 10 lines(ish).

  21. Scala Times Issue #308

    Towards more functional Play  -  Part 1. ZIO environment meets constructor-based dependency injection. How-to run tests in parallel with sbt. Learn myself some Scala 3, episode 4: strict equality. 5 pitfalls to avoid when starting to work with ZIO.

  22. Scala Times Issue #307

    Standardizing IO Interfaces for Scala Libraries. WebSocket Streaming with Scala. State of Monocle. Scala tooling in 2019. How to Work with Scala Collections in Java.

  23. Scala Times Issue #306

    2019 Scala Developer Survey . Lessons Learned Building a Van Laarhoven Lens Library. A Glossary of Functional Programming. Tips for moving from tut to mdoc. Notes on Category Theory in Scala 3 (Dotty).

  24. Scala Times Issue #305

    Beyond Liskov: Type Safe Equality in Scala. Scala 2 Roadmap Update: the Road to Scala 3. Explicit nulls are in!. Functional Scala London 2019: Day 1. Leveraging Monoids for More Powerful Summarization.

  25. Scala Times Issue #304

    Akka references serialization with Protobufs (up to Akka 2.5). TMWL November’19 — ScalaTest, Medusa, PW-Sat2 cubesat. Implement your future with ZIO. Decouple the Program from its Implementation with ZIO modules. ZIO environment and modules pattern: zio, scala.js, react, query management.

Organizing an event?
Promote it with
Scala Times.
The Scala Times reader?
Get a banner!
Got a tip?Send it in!
Follow us onTwitter.
Curated bySoftwareMill.
We arehiring.
Andtaking on projects.