A free, once-weekly Scala news flash. Easy to unsubscribe. Goes out every Thursday.
March 28th, 2019, ISSUE 267

READING

Bloop’s compiler performance is ~29% faster than SBT

... on at least one project.
Alvin Alexander (@alvinalexander)
Fourth batch of Scala 3 SIPs

Proposal to add Opaque Type Aliases, to remove Symbol literals, to add Type lambdas, to add Extension Methods, to add Top-level definitions, and to add Kind Polymorphism.
The SIP Committee
Functional Hangman with ZIO

Slight changes from John’s version include the new type signature of course, and the use of ZIO.succeed (instead of IO.now). Also a slight enhancement that I added was to tell the player what the correct answer was when they lose.
Alvin Devlin
Scala: Understanding Variance

The use of variance in the type system allows us to make intuitive connections between complex types, whereas the lack of variance can restrict the reuse of a class abstraction.
Ayush Mittal
Back-Pressure implementation: AWS SQS polling from a sharded Akka Cluster running on Kubernetes

The solution was to inform SQS Batch Poller Actor about the state of unprocessed SQS messages(Workload) in the system. i.e implementing Back-Pressure.
Rohit Sharma
Fun with mutually-recursive typeclass resolution

I’ve had to write a few instances of Sangria'sInputType by hand, which had me wondering if they could be derived automatically.
Tim Spence
IntelliJ Scala Plugin 2019.1

Highlighting For-comprehensions, Find Usages for Implicits, and More.
Pavel Fatin

PRESENTATIONS

Questionable Typeclass Encoding in Scala

In this video we will ask questions like: "Why are Scala's type classes not encoded differently?" or "Is having more types always better?" and I don't claim to have all the answers.
DevInsideYou (@DevInsideYou)

EVENTS

ScalaUA, Kiev, Ukraine, March 29th - 30th

Use promo code ScalaTMS%_ScAlAUA-2019-29-30 for 20% discount for our readers!
ScalaUA (@ScalaUA_Conf)
Scalar, Warsaw, Poland April 5th - 6th

Join the next edition of the largest Scala conference in central Europe!
SoftwareMill (@softwaremill)
flatMap(Oslo), Oslo, Norway, May 8th - 9th

Use promo code SCALATIMES for a discount for our readers!
flatMap(Oslo) (@flatmaposlo)
CFP for LX Scala & Reactive, Lisbon, Portugal, July 4th - 5th

Don't miss the CFP deadline which is May 1st!
LX Scala & Reactive (@LX_Scala)
CFP for Lambda World, Cádiz, Spain, October 17th - 18th

Deadline for submissions is June 1st.
Lambda World (@lambda_world)
CFP & free ticket for BeeScala, Ljubljana, Slovenia, November 21st - 23rd

Answer the question: "What is the idea behind the BeeScala name?", send your reply to info@bee-scala.org by 31st of March. For some lucky person, there's one free ticket waiting!
Bee Scala (@BeeScalaConf)
CFP for Scala Italy, Bologna, Italy, September 20th - 21st

Submit your proposal before May 5th.
Scala Italy (@ScalaItaly)

RELEASES

scala-newtype

NewTypes for Scala with no runtime overhead.
Cary Robbins (@carymrobbins)

VARIA

Scala Times banners?

Want one? Click here
THE INTERNET
Scala Times stickers?

Want one? Let us know or tweet @scalatimes.
THE INTERNET





  1. Scala Times Issue #270

    Akka 2.6 roadmap. Extending MapR Database Queries Using Scala Polymorphic Types. Marvels of functional programming: Composing effects with monads. Traverse your HLists for fun and profit. Did Functional Programming get it wrong?.


  2. Scala Times Issue #269

    Scalar 2019 whiteboard voting. 38 lines of code towards better data validation in Scala. Scala: Internals and Intermediates. Hacker News API Part 5. Scala Ordering Crash Course.


  3. Scala Times Issue #268

    Functional Hangman with ZIO. Scala or Go: Tastes Great or Less Filling?. An Example of Free Monads and Optimization. Homegrown Scala Collections - Part 29 - Are Views Typeclasses?. Scalar, Warsaw, Poland April 5th - 6th.


  4. Scala Times Issue #267

    Bloop’s compiler performance is ~29% faster than SBT. Fourth batch of Scala 3 SIPs. Functional Hangman with ZIO. Scala: Understanding Variance. Fun with mutually-recursive typeclass resolution.


  5. Scala Times Issue #266

    The RedMonk Programming Language Rankings: January 2019. A monad is not a burrito. Joins in Apache Spark - Part 3. Scala sbt Project Directory Structure. Scala Snippets #1: Instantiable Implicits.


  6. Scala Times Issue #265

    Testing Incrementally with ZIO Environment. Finally Tagless - Not Quite Dead Yet. Functional Testing with Tagless-Final. Monad Transformers aren’t hard!. The Functional Scala Concurrency Challenge.


  7. Scala Times Issue #264

    Final Tagless seen alive. Effectful Episode with John de Goes. State vs Stateful Actor. Phil Bagwell Nominations. Introduction to Akka Streams.


  8. Scala Times Issue #263

    Describe, then interpret: HTTP endpoints using tapir. Vue.js with Playframework. Mu-RPC: defining messages and services. Validate Service Configuration in Scala. Modern Systems Programming And Scala Native With Richard Whaling.


  9. 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.


  10. 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.


  11. 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?.


  12. 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….


  13. 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.


  14. 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.


  15. 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).


  16. 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.


  17. 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.


  18. 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.


  19. 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.


  20. 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.


  21. 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.


  22. 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.


  23. 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.


  24. 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.


  25. 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.


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.