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January 21st, 2021, ISSUE 362


Essential Effects

A book for learning effectful programming in Scala. Learn how to safely create, compose, and execute effectful Scala programs using the Typelevel Cats Effect library.
Adam Rosien (@arosien)
5 Blogs for Scala's Birthday

The public release of Scala was 17 years ago today. Here is a list of my favourite active Scala blogs.
Adam Gordon Bell (@adamgordonbell)
Monocle 3 Roadmap

A peek into the Future.
Julien Truffaut (@TheFpTower)
Higher-kinded data in Scala

Higher-kinded data is a reasonably well-known concept in the Haskell world, but I haven’t seen many people talking about it in Scala. I’ll use a real-world example to explain the concept and show how it can be useful.
Chris Birchall (@cbirchall)


Objects and Companions in Scala

In this video we'll explore Scala objects, which implement the singleton pattern in a single line of code.
Daniel Ciocîrlan (@rockthejvm)


Essential Effects, 27th-29th January, Online Event

This course introduces Cats Effect as a tool for building resource-safe and concurrent applications. (US timezone). Use code 'scalatimes' for a 15% discount!
Inner Product (@InnerProductLLC)
Lambda Days 2021, 16th - 19th February, Virtual Event

Don't forget to check the Diversity Scheme - we have a pool of tickets to be distributed among participants from groups underrepresented in IT.
LambdaDays (@LambdaDays)
ZIO World, 1st March, Online Event

Join ZIO users and contributors for the inaugural ZIO World, which reveals ZIO 2.0, providing inspiration and new opportunities to create the most powerful reactive applications on the JVM. FREE of charge for all ZIO Contributors and Users.
Ziverge (@zivergetech)



A library for validation combinators in Scala.
combos contributors
Akka 2.6.11

A bunch of improvements and bugfixes, enjoy!
Akka team (@akkateam)
Scala Native 0.4.0

A lot of updates and changes (including breaking changes), as well as bugfixes.
Scala Native contributors
Kamon APM

Kamon has a new website, and improved APM product, available in a free plan as well!
Kamon Team (@kamonteam)

  1. Scala Times Issue #368

    Scala 3 Tech Report. Tuples bring generic programming to Scala 3. Scala Cats Invariant Functor. Lean for Scala programmers. Structuring Services with ZIO and ZLayer.

  2. Scala Times Issue #367

    The Coralogix Operator: A Tale of ZIO and Kubernetes. Introducing the lihaoyi-scala Github Organization. Why Are Fibers Fast?. Implementing a CountDownLatch (async and dirty). Value Classes in Scala.

  3. Scala Times Issue #366

    GraphQL Overview  -  Part2  -  Libraries. Scala's List has a Secret. Preventing Version Conflicts with versionScheme. Scala 3 Survey: The Conclusion. Upgrade your Tagless Final with Tofu.

  4. Scala Times Issue #365

    Coding Adventures with Party Parrot Game . Scala Cats Contravariant Functors. From First Principles: Why Scala?. Idiomatic Error Handling in Scala. Stop Letting Your Tests “Make” Your Luck.

  5. Scala Times Issue #364

    Why we need yet another Akka Persistence plugin?. Match Types in Scala 3. A Metals Retrospective (Part 1) · Metals. Making the Spark DataFrame composition type safe(r). Type driven API development using Scala and Tapir.

  6. Scala Times Issue #363

    How to Sort Lists in Scala with Tail Recursion. Image editing with Functors. Tail Recursive Functions (in Scala). Algebraic Data Types (ADT) in Scala. Ep 6: Functional error handling with applicative in Scala 3.

  7. Scala Times Issue #362

    5 Blogs for Scala's Birthday. Monocle 3 Roadmap. Higher-kinded data in Scala. Objects and Companions in Scala. Essential Effects, 27th-29th January, Online Event.

  8. Scala Times Issue #361

    Scala 3: Dependent Types, Part II. Configuring and suppressing warnings in Scala. Threading best practices in Cats Effect. Scala 3 Metaprogramming by Example by Adam Warski. What the Functor?.

  9. Scala Times Issue #360

    Scala 3: Dependent Types, Part I. Publish Scala 2 and Scala 3 macros together. Concurrent state machines. Wire Signals - Yet Another Event Streams Library. Scala Love CFP.

  10. Scala Times Issue #359

    Implementing Type classes in Scala 3. Finite-State Machines + FS2 streams: A match made in heaven. Scala Compiler Options, Fatal Warnings and Linting Guide. ZLayers by example. Scala 3 type classes.

  11. Scala Times Issue #358

    VirtusLab’s Scala 3 cooperation update. Scala 3.0.0-M3: developer's preview before RC1. How to Use Thread.sleep Without Blocking on the JVM. New in Scala 3. Scala Love CFP.

  12. Scala Times Issue #357

    Join the Scala Discord Server!. Enforcing Semantic Versioning with sbt-strict-update. Kafka Cron using wix/greyhound. Scala Filesystem Operations (paths, move, copy, list, delete) . Metals 2020 Review.

  13. Scala Times Issue #356

    Scala 3 Developers' Survey. Tapir vs Endpoints4s. Opaque Type Aliases and Open Classes. Akka Platform Guide. Type classes with Scala 2.

  14. Scala Times Issue #355

    Scala 3 Developers' Survey. Four new features of Scala 2.13 releases that you probably missed. Scala 3: Path-Dependent Types, Dependent Methods and Functions. Message-based Parallelism with Actors. IntelliJ Scala Plugin 2020.3 Is Out!.

  15. Scala Times Issue #354

    Scala 3 Developers Survey. A case for akka-coordination lease. Monad transformers and cats  -  3 tips for beginners. Forward Compatibility for the Scala 3 Transition. Mirror, Mirror on the Wall, Who’s the Genericioust of Them All?.

  16. Scala Times Issue #353

    Scala 3 Developers Survey. Managing Database Migrations in Scala. One year with Akka 2.6. Best practice for natural Ordering. Event-driven railway network based on Pulsar.

  17. Scala Times Issue #352

    Domain-Driven Design with FP in Scala. Explicit term inference with Scala 3. Keep alive for JMS connections. Why You Should Learn Scala in 2020?. A step-by-step guide for debugging memory leaks in Spark Applications.

  18. Scala Times Issue #351

    Autorecovery for (JMS) Streams. ZIO-AWS with ZIO Query. Implementing Scala.js Support for Scala 3. Let’s Talk About the Scala 3 Indentation. Concurrency in Cats Effect 3.

  19. Scala Times Issue #350

    Designing tapir’s WebSockets support. BSP Support in sbt 1.4. Streaming With Probabilistic Data Structures: Why & How. Scala 3 Migration guide. ScalaZONE - Scala 3 Programming Language Courses.

  20. Scala Times Issue #349

    Generic IOApp alternative. Let's build a Scala mock library. How To Make Integration Tests Less Flaky. Option  - the null of our times. Top Link of September: Polynote, A better notebook for Scala.

  21. Scala Times Issue #348

    Java 15 through the eyes of a Scala programmer. Functional Design, October 20th - 22nd, Online training. Scale By the Bay, November 12th - 14th, online event. Functional Data Modeling, November 18th - 19th, Online training. ZIO Hackathon, November 20th-21st, online event.

  22. Scala Times Issue #347

    A short guide to Blocker. Using: Did they forget something?. The assignment operator is broken!. Attending a hackathon with Scala and Akka (Streams) on Microsoft Azure. Programming Scala, Third Edition.

  23. Scala Times Issue #346

    Getting Started with Knative in Scala. Tagless Final - Part 12 - delivery-http-http4s (The Big Rewrite). Programming in Scala for beginners - week 5: classes. Eyjafjallajökull Lecture 2019. Scala 3: Enums.

  24. Scala Times Issue #345

    Tour of Scala. Polynote, A better notebook for Scala. Single command Scala setup. Dotty becomes Scala 3. Functional Effects with ZIO.

  25. Scala Times Issue #344

    Can we build better?. Algebra and Parametricity. How to Deploy a Scala Application to AWS Lambda. 5 lessons learned from my continuing awesome journey with ZIO. Scala 3 - A community powered release.

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