scala

• Scala 2.x uses universal equality which allows comparison of Int and String. Dotty introduces "multiversal" strictEquality that works similar to Eq typeclass.
• Currently both Scala 2.x and Dotty use Java's == to compare unboxed primitive types. This mixes comparison of Int with Float and Double etc.
• Float is narrower than Int, and Double is narrower than Long.
• Because Scala transparently boxes Int into java.lang.Integer as (1: Any), it implements cooperative equality for == and ##, but not for equals and hashCode, which emulates widening for boxed primitive types. Many people are unaware of this behavior, and this could lead to surprising bugs if people believed that equals is same as ==.
• We might be able to remove cooperative equality if we are willing to make unboxed primitive comparison of different types 1L == 1 an error.

giter8.version

I added a small app called giter8-launcher for Giter8 0.12.0. The purpose of the app is to make the behavior of the Giter8 template more predictable. Today, template authors may create a template for some version of Giter8 X, but the users might use some other version of Giter8 Y that ships with "sbt new."

Pamflet is a publishing application for short texts, particularly user documentation of open-source software.

Pamflet 0.8.2 updates its monospace typeface to SFMono, and undoes the incidental pink color that got introduced when I migrated from Blueprint to Bootstrap.

The semantics of a dependency resolver determine the concrete classpath based on the user-specified dependency constraints. Typically the differences in the details manifest as different way the version conflicts are resolved.

• Maven uses nearest-wins strategy, which could downgrade transitive dependencies
• Ivy uses latest-wins strategy
• Coursier generally uses latest-wins strategy, but it's tries to enforce version range strictly
• Ivy's version range handling goes to the Internet, which makes the build non-repeatable
• Coursier orders version string completely differently from Ivy

• Expecty 0.12.0
• Expecty 0.13.0

This is a second post on installing your own JDKs on Travis CI. Previously I've written about jabba.

Today, let's look at SDKMAN!, an environment manager written by Marco Vermeulen (@marc0der) for JDKs and various tools on JVM, including Groovy, Spark, sbt, etc.

AdoptOpenJDK 11 and 8

Update 2020-09-23: Updated the regex of version number.

Over the holiday break I've implemented left TOC for Pamflet, and released it as Pamflet 0.8.0.

As of Scala 2.13.0-M5, it's planned that scala.Seq will change from scala.collection.Seq to scala.collection.immutable.Seq. Scala 2.13 collections rework explains a bit about why it's been non-immutable historically. Between the lines, I think it's saying that we should celebrate that scala.Seq will now be immutable out of the box.

Defaulting to immutable sequence would be good for apps and fresh code. The situation is a bit more complicated for library authors.

• If you have a cross-built library, and
• if your users are using your library from multiple Scala versions
• and your users are using Array(...)

this change to immutable Seq could be a breaking change to your API.

This post was coauthored by Eugene Yokota and Yifan Xing.

We need to change the culture around tech conferences to improve the inclusion of women (and people from other backgrounds too!). For that, there needs to be clear signaling and communication about two basic issues:

1. No, it's not ok to hit on women at a conference.
2. Assume technical competence, and treat women as professional peers.

These points should be communicated over and over at each conference before the keynote takes place, and before socializing hours.

Compile, or compile not. There's no warning. Two of my favorite Scala compiler flags lately are "-Xlint" and "-Xfatal-warnings".
Here is an example setting that can be used with subprojects:

ThisBuild / organization := "com.example"
ThisBuild / version      := "0.1.0-SNAPSHOT"
ThisBuild / scalaVersion := "2.12.6"
 
lazy val commonSettings = List(
  scalacOptions ++= Seq(
    "-encoding", "utf8",
    "-deprecation",
    "-unchecked",
    "-Xlint",
    "-feature",
    "-language:existentials",