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February 6th, 2020, ISSUE 313

READING

Happy eyeballs algorithm using ZIO

Living in the Scala world, a natural question arises: what would this look like in Scala? After all, Scala is the language to tame concurrency problems!
Adam Warski (@adamwarski)
How (not) to use shapeless for cross-layer conversions in Scala

Jsonifying class field names? Let’s try to accomplish the task using shapeless.
Mikołaj Koziarkiewicz (@mikolak_net)
So you want to compose some functions

There are monoids for functions, and you can use these to get some nice compositions.
Lars Hupel (@larsr_h)
RESTful error handling with Akka HTTP and the library “endpoints”

Implementing RESTful services comes with challenges, this article addresses two of them: keeping a uniform representation of technical and business errors, and reducing the cost of maintaining the documentation.
Julien Richard Foy (@julienrf)
MUnit is a new Scala testing library · MUnit

You may be thinking "Why create Yet Another Scala testing library?". It's a good question and this post is my attempt to explain the motivations for creating MUnit.
Ólafur Páll Geirsson (@olafurpg)
Identify Side Effects And Refactor Fearlessly

In this article we will solely focus on the aspect of side effects and strictly speaking on how to identify them.
Leif Battermann (@leifbattermann)
5 (more) pitfalls to avoid when starting to work with ZIO

Second part of the series.
Natan Silnitsky (@NSilnitsky)
GraphQL in Scala with Caliban - Part 2 - Query optimization

It is very common to have deeply nested schemas where each inner field might require gathering data from a database. Ideally, we’d like to keep these calls to a minimum.
Pierre Ricadat (@ghostdogpr)
Announcing Dotty 0.22.0-RC1 - syntactic enhancements, type-level arithmetic and more

The version brings syntactic enhancements for extension methods and context parameters, as well as the kind projector syntax.
Anatolii Kmetiuk (@AKmetyuk)
Hack: How to Use Scala Futures with Cats IO

The article demonstrates a common trap you might fall into during the integration process.
Tamas Polgar (@TamasPolgar)
Dependency Injection using Self Types in Scala (Cake Pattern)

Self-types in action? Piece of cake!
Sayan Chakraborty
K-Means clustering with Apache Spark and Zeppelin notebook on Docker

Running ML model with IntelliJ IDEA on local spark environment.
λ.eranga (@itseranga)
Beating Textbook Algorithms in String Search

Performance of string search algorithms in Scala.
Linas Medžiūnas (@LinasMedziunas)
Vectos - Tracing with cats-tagless and ZIO

A nice tool to do root cause analysis and find bottlenecks.
Mark de Jong (@mark_dj)
Checklist for learning Scala

Based on this experience and the idea of lean learning: the right setting for everyone who wants to start a journey with Scala.
Horia Constantin (@ConstantinHoria)
Scala for Python developers

How to switch to Scala?
Antoine Doeraene (@doe_antoine)
Pure Function vs Referential Transparency

A manual of the problem solver.
Edward Huang
Part 1: Application of literal and dependent object types in Scala 2.13

How parametrization of a function with unconstrained String literals lures engineers to write not reliable software and how type-unsafe functions can become safe with an alternative design, which combines literal types, dependent-object types, and type class instances.
Yevgen Nerush (@nerush)

PRESENTATIONS

Data Juggling - Part 3 - Optics Explained (Monocle - Part 2)

In this video we will take a look at Isos, Prisms, Optionals and of course Lenses. We will also briefly touch upon Folds and Traversals.
DevInsideYou (@DevInsideYou)
Basic streams and combinators in fs2

In this video, you'll learn about basic streams and operators from the fs2 library. You'll also learn some of what makes fs2 Stream different than the typical collection.
Jakub Kozłowski (@kubukoz)

EVENTS

Scalar, March 19th-21st 2020, Warsaw, Poland

Get ready for the workshop-driven FP event in Poland!
SoftwareMill (@scalarconf)
ZIO Hackathon, March 22nd-23rd 2020, Warsaw, Poland

Over the course of two days, we will share and learn about ZIO and related projects; chat about functional programming, functional Scala, and much more; work on fun projects; and get to know one another.
Ziverge (@zivergetech)
ScalaUA, April 3th-4th 2020, Kyiv, Ukraine

Wholesale 10+ tickets are available till 2020.04.02.
ScalaUA (@ScalaUA_Conf)
flatMap(Oslo), May 14th-15th 2020, Oslo, Norway

The call for papers are open til until 1st of March. Also, user our link for a special discount for Scala Times readers!
flatMap(Oslo) (@flatmaposlo)

RELEASES

cats-effect 2.1.0

New SyncEffect typeclass, Concurrent#background function, Resource is now covariant in both its F[_] and A, There is now a Parallel instance for Resource, Scala.js 1.0 support and many more updates!
cats-effect contributors
zio-logging

Simple, idiomatic logging for ZIO apps, with tracing and pluggable backends out of the box.
zio-logging contributors
sbt 1.3.8

Fix for Coursier resolvers so the project resolvers come first, also a fix for Zinc causing intermittent NullPointerException.
sbt contributors

VARIA

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