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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


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  1. 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.

  2. 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.

  3. 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.

  4. Scala Times Issue #237

    Instantiate case class with arbitrary values to reduce verbosity in tests. Homegrown Scala Collections - Part 2 - Unit Testing with ScalaTest. Lambda World Seattle, September 17th - 18th . Lambda World Cádiz, Spain, October 25th - 26th, 2018. Scala Wave, September 6th - 8th, 2018, Gdańsk, Poland.

  5. Scala Times Issue #236

    Streaming data from PostgreSQL using Akka Streams, Akka Http and Doobie. Lambda World Seattle, September 17th - 18th . Lambda World Cádiz, Spain, October 25th - 26th, 2018. Scala Wave, September 6th - 8th, 2018, Gdańsk, Poland. Scala Italy, September 14th-15th, Florence.

  6. Scala Times Issue #235

    Akka Http Websocket Example. Akka HTTP Request and Response models. Composable table updates in Slick. Cask: a Scala HTTP micro-framework. Actor Model Explained.

  7. 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.

  8. 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.

  9. 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.

  10. 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 .

  11. 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 .

  12. 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.

  13. 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.

  14. 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 .

  15. 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 .

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  21. 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.

  22. 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.

  23. 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.

  24. 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!.

  25. 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.

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