A free, once-weekly Scala news flash. Easy to unsubscribe. Goes out every Thursday.
September 20th, 2018, ISSUE 240


2018 Scala compilation time survey

We have created a survey to understand how much time is lost in 2018 by Scala developers because of compilation. Your answers will greatly help get a better understanding of the problem.
Mirco Dotta
How to Dockerise a Scala and Akka HTTP Application

Using Docker is a given nowadays, and in this tutorial we will how to learn to dockerise our Scala and Akka HTTP applications without even creating a Dockerfile ourselves.
Using Machine Learning to Predict the Weather in Basel

Pt. 1 Data & Baselines
Matthias Langer (@mlangc)
How We Found a Missing Scala Class

Here’s a fun tale of debugging that starts off with a common alert nagging our on-call rotation, leads us to a very confusing NoClassDefFoundError, and ends up with us knowing a lot more about dynamic tracing in the JVM.
Ivan Vergiliev (@IvanVergiliev)
Traversing Object Graph with Shapeless (and Why You Should Write the Same Code Twice)

See how the power of Shapeless can be leveraged for serialization.
Shani Elharrar (@shanielh)
New proposal for extension method

Compared to #4114, this one is simpler and integrates out of the box with implicits.
Martin Odersky (@Odersky)
New pretty id generator

UUIDs are cool, but sometimes you need to generate a user-friendly identifier. Here's an example of how to do it in Scala.
Łukasz Żuchowski
Code formatting: scalafmt and the git pre-commit hook

Learn how to trigger automatic code formatting just before the commit.
Alo Davì
The Business Case for Functional Programming

Functional programming will limit your technical debt so you build better software faster than you imagined and will earn you the Tesla you always wanted. Here's why.
Neil Chaudhuri
Scala Programming - A Skeptic's Journey

While Scala has much to offer that I won’t cover (e.g., type classes and functional programming constructs for managing side-effects), I think it is useful to consider what are those things that are most accessible to developers coming from a Java/C++ ecosystem.
Dean Povey


Homegrown Scala Collections - Part 5 - Linked Set

In this video we are going to revamp our initial implementation of Sets, since it offered no way to link elements of a Set to each other and thus prevented us from implementing methods like isSubsetOf.
DevInsideYou (@DevInsideYou)


Lambda World Cádiz, Spain, October 25th - 26th, 2018

Use promo code STLW18 for Scala Times readers to get 10% discount!
47 degrees (@47deg)
Win a ticket to Lambda World, Cadiz!

Enter the competition to win a free ticket.
Signify Technology (@Signify_Tech)
Scala Up North, Toronto, CA, September 28th-29th, 2018

Use our promo link and get a 10% discount!
Scala Up North (@ScalaUpNorth)
Win tickets and a return flight to Scale By The Bay, San Fracisco

All you have to do is refer a Scala friend! Simply enter for the opportunity to be at Scale by the Bay by emailing us!
Signify Technology (@Signify_Tech)



Plugin that integrates with iTerm2 on MacOS.
Johan Andren (@apnylle)

An sbt plugin to check that your libraryDependencies accurately reflects the libraries that your code depends on in order to compile.
Chris Birchall (@cbirchall)
scalajs-react 1.3.0

With support for React 16.5, moar type-safety, other features.
scalajs-react contributors
Scalameta v4.0.0

A library to read, analyze, transform and generate Scala programs. New website and a lot of updates!
Scalameta contributors


Scala Times banners?

Want one? Click here
Scala Times stickers?

Want one? Let us know or tweet @scalatimes.

  1. Scala Times Issue #262

    Is your Scala object always a singleton?. Freer doesn’t come for free. Maintaining Binary Compatibility in Scala. Anatomy of functors and category theory. A little Scala 'sed' class.

  2. Scala Times Issue #261: from Scala with love

    Aecor — Purely functional event sourcing in Scala. Part 5. Homegrown #Scala Collections - Foldable Maps. Kubernetes Liveness and Readiness Probes Revisited. Streams and Resource Safety | Akka. Assemble messages from Akka Actors.

  3. Scala Times Issue #260

    Cats Ecosystem Community Survey 2018 Results. Thread Pool Best Practices with ZIO. Purely functional parallelism in Scala. Finatra meets Ammonite. Typed Supervision: why the changes?.

  4. Scala Times Issue #259

    State of Scala compilation time in 2018. Low-memory symbol indexing with bloom filters. Finally: Top-level Definitions. Why you should think about functional programming. Toward a polyglot James server….

  5. Scala Times Issue #258

    Scala Days 2019 - Celebrating Collaborative Success. Scala community build grows, adds Scala 2.13 and JDK 11. Type-checked triple equals: Scala test. Using Scala Plugins From Gradle. Exploring Explicit Nulls in Dotty.

  6. Scala Times Issue #257

    High-Performance Functional Programming Through Effect Rotation. Trampolines for Everything. This month at SoftwareMill we’ve learned — December’18. A Guide to Scala Collections: Exploring Monads in Scala Collections. Spark Custom Stream Sources.

  7. Scala Times Issue #256

    Where is the llama for FS2?. Scala Best Practices - Foreword. Aecor - Purely functional event sourcing in Scala. Part 4b. Postgresql from Spark, how to query?. Error Handling in Akka Actor (with Future).

  8. Scala Times Issue #255

    ADT through the looking glass - lenses, prims and other optics. Hpc with scala and akka Actors. Scala Type Classes - The Name Printer. Evolutionary Algorithms on the JVM via Scala  -  a minimal introduction. Aecor - Purely functional event sourcing in Scala. Part 4a.

  9. Scala Times Issue #254

    Cats Ecosystem Community Survey 2018. Scala Developer Suvey Results 2018. Minutes of the 11th meeting of the Scala Center, Q4 2018. Software as a Reflection of Values With Bryan Cantrill. Dotty: An Alternative to Implicits.

  10. Scala Times Issue #253

    Scala Variables - Syntax, Declaration, Use case, Examples - Leo Benkel. Fast goto definition with low memory footprint · Metals. New Akka Getting Started Guide. Different ways to understand a monad. MOOC: Introduction to programming with dependent types in Scala.

  11. Scala Times Issue #252

    The F-words: functor and friends. Grafter  -  a take on yet another DI library. Anatomy of a Scala quirk. Creating Work Queues with Apache Kafka and Apache Pulsar. Terminus - Cross Platform Terminal Emulator for Sublime Text.

  12. Scala Times Issue #251

    Scala Numerical Performance with Scala Native and Graal. SBT Plugin - How to make it, debug it, improve it?. Better than IO, part 1. Scala and Slick - An Introduction. Category Theory for Programmers: Scala Edition 1.1-RC.

  13. Scala Times Issue #250

    Correlation IDs in Scala using Monix. Further enhance `new` syntax to reduce boilerplate. Counting type inhabitants. Variances in Scala. SIP Meeting Minutes - November 1-3 2018.

  14. Scala Times Issue #249

    How To Exclude Scala Tests With Tagging?. Explore Witnesses as an Alternative to Implicits. Build code analyzers with Scalameta and Scalafix. Immutable State in Real World. A streaming library with a superpower: FS2 and functional programming.

  15. Scala Times Issue #248

    Minutes of the 10th meeting of the Scala Center, Q3 2018. Scala - faster and slimmer with GraalVM. 5 themes for Scala programming in 2019. Beyond the conference: Q&A with The Guardian’s Maria-Livia Chiorean. Homegrown Scala Collections - Part 13 - Growing Binary Search Trees.

  16. Scala Times Issue #247

    Getting started with recursion schemes using Matryoshka. Friendly Functional Programming. Building the Hangman Game using ScalaZ ZIO. Anatomy of semigroups and monoids. The Scala 2.12 / 2.13 Inliner and Optimizer.

  17. Scala Times Issue #246

    Don’t get mixed. Typed Functional Programming and Software Correctness. Scala compiler phases with pictures. A tale on Semirings. Scala Programming  -  A Skeptic’s Journey.

  18. Scala Times Issue #245

    Scala Center highlights June - October. Fastparse 2: Even Faster Scala Parser Combinators. God’s Programming Language With Philip Wadler. Algebraic Data Types in four languages. Finch Performance Lessons.

  19. Scala Times Issue #244

    Achieving stack and heap safety in recursive functions. A comprehensive introduction to Cats-mtl. Using Akka Http to create a test server. Skoda's new hatchback is called 'Scala'. Are you sure your AnyVals don’t instantiate?.

  20. Scala Times Issue #243

    Introducing Scaladoc Tables. This month at SoftwareMill we’ve learned. Backoff and Retry Error-Handling for Akka Streams. Anatomy of functional programming. Anatomy of an algebra.

  21. Scala Times Issue #242

    Using Monix with Kafka, Avro and Schema Registry. Scala is now on Apache License Version 2.0. Just Enough Scala for Spark Programmers. Giter8 Scala Microservice template. Homegrown Scala Collections - Part 7 - Parametric Polymorphism aka Generics.

  22. Scala Times Issue #241

    Model correctly and write less code, using Akka Streams. Elevator Control System using ZIO. Easing Into Cats, And The Case For Category Theory Inspired Abstractions. Get considered harmful. IO & Logging Capabilities.

  23. Scala Times Issue #240

    2018 Scala compilation time survey. How to Dockerise a Scala and Akka HTTP Application. Using Machine Learning to Predict the Weather in Basel. How We Found a Missing Scala Class. New proposal for extension method.

  24. Scala Times Issue #239

    Functional Programming for Mortals. Strings are not the type you are looking for. Choose Primitives for Typelevel and Meta Programming in Scala 3.0. To tag a type. Parallelize tests in SBT on Circle CI.

  25. Scala Times Issue #238

    How to translate your API with Shapeless. A case to introduce Scala in a Java world. Are Scala Futures the past?. Effect Extensions Pattern. Dotty Type classes.

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.