I’m happy to announce sbt 1.3.11 patch release. Full release note is here - https://github.com/sbt/sbt/releases/tag/v1.3.11.
Special thanks to Scala Center. It takes time to review bug reports, pull requests, make sure contributions land to the right places, and Scala Center sponsored me to do maintainer tasks for sbt during May. Darja + whole Scala Center crew have been chill to work with.
Normally changing the project/build.properties to
Jar Jar Abrams is an experimental Scala extension of Jar Jar Links, a utility to shade Java libraries.
For library authors, the idea of other library is a double-edged sword. On one hand, using other libraries avoids unnecessary duplication of work, not using other libraries is almost hypocritical. On the other hand, each library you add would add a transitive dependency to your users, increasing the possibility of conflict. This is partly due to the fact that within a single running program you can one have one version of a library.
In sbt core concepts talks I’ve been calling sbt a casually functional build tool. Two hallmarks of functional programming are that it uses immutable data structure instead of mutation, and that it gives attention to when and how effects are handled.
From this perspective, we can think of setting expressions and tasks to be those two things:
Anonymous settings are represented using Initialize[A], which looks like this:
build.sbt is a DSL for defining a task graph to be used for automatic parallel processing. The message passing among the tasks are expressed using something.value macro, which encodes Applicative composition (task1, task2) mapN { case (t1, t2) => .... }.
One mechanism I’ve been thinking about is allowing some long-running task1 to communicate with task2 midway.
Normally, we would break down task1 into two subtasks. But it might not be as straight-forward to implement such thing. For example, how would be tell Zinc to compile something halfway, and resume later? Or tell Coursier to resolve, but fetch later?
I’m happy to announce sbt 1.3.10 patch release. Full release note is here - https://github.com/sbt/sbt/releases/tag/v1.3.10
Normally changing the project/build.properties to
sbt.version=1.3.10
would be ok. However, given that the release may contain fixes to scripts and also because your initial resolution would be faster with *.(zip|tgz|msi) that contains all the JAR files, we recommend you use the installer distribution. They will be available from SDKMAN etc.
I’ve just released Zinc 1.4.0-M1. Note this is a beta release and it won’t be compatible with future 1.4.x, but I chose a commit fairly close to 1.3.x so it should be usable.
java.util.Date with java.time zinc#714 by @slandelleZinc is an incremental compiler for Scala. Though Zinc is capable of compiling Scala 2.10 ~ 2.13 and Dotty, thus far Zinc itself has been implemented using Scala 2.12. This is fine for sbt 1.x, which is also implemented in Scala 2.12, but there’s been requests to cross build Zinc for 2.13.
This is part 3 of the post about sbt-projectmatrix, an experimental plugin that I’ve been working to improve the cross building in sbt. Here’s part 1 and part 2. I’ve just released 0.5.0.
After adding sbt-projectmatrix to your build, here’s how you can set up a matrix with two Scala versions.
ThisBuild / organization := "com.example"
ThisBuild / scalaVersion := "2.12.10"
ThisBuild / version := "0.1.0-SNAPSHOT"
lazy val core = (projectMatrix in file("core"))
.settings(
name := "core"
)
.jvmPlatform(scalaVersions = Seq("2.12.10", "2.11.12"))
Read More…
I joined Lightbend (then Typesafe) in March, 2014. After six incredible years April 7, 2020 was my last day. I am grateful that I got the opportunity to work with an amazing group of people at Lightbend, partners, customers, and various people I got to meet at conferences. Looking back, before COVID-19 times, it’s almost surreal that I was flying to Europe, Asia, and North America every few months to attend conferences and tech meetings.
Last week I wrote about #8820, my proposal to add user-land compiler warnings in Scala. The example I had was implementing ApiMayChange annotation.
package foo
import scala.annotation.apiStatus, apiStatus._
@apiStatus(
"should DSL is incubating, and future compatibility is not guaranteed",
category = Category.ApiMayChange,
since = "foo-lib 1.0",
defaultAction = Action.Warning,
)
implicit class ShouldDSL(s: String) {
def should(o: String): Unit = ()
}
Read More…
serves 4?
put cold water in a large dutch oven with 5 dried shiitake and similar amount of dried kombu kelp. let it sit for a few hours covered.
As a library author, I’ve been wanting to tag methods in Scala that can trigger custom warnings or compiler errors. Why would I want to intentionally cause a compiler error? One potential use case is displaying a migration message for a removed API.
Restligeist macro: n. A macro that fails immediately to display migration message after implementation has been removed from the API.
— ∃ugene yokot∀ (@eed3si9n) August 30, 2016
For example, if you try to use <<= in sbt 1.3.8 you’d get the following error on load:
4h 35m
The relationship given to Int and Long should be exactly the same as the relationship third-party library like Spire can write UInt or Rational with the first-class numeric types.
1 == 1L an error under strictEqualityFromDigitsI want to understand how equality works in Scala. It’s a complicated topic that’s been going on for ten years.
Major concerns are:
nullF[+A])Understanding equality means knowing how these combinations are compared.
The language spec provides some hints, although it does not have the full information. Chapter 12 contains the definition of Any as follows:
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.”
One of the neat ideas about sbt is that no matter what version of sbt script users might have it installed, the core sbt version is specified by the build author using project/build.properties file. This significantly reduces the it-only-works-on-my-machine problem. giter8-launcher is analogous to sbt’s sbt-launcher. giter8-launcher clones the template and reads project/build.properties file to determine the Giter8 version to render the template.
Template authors can now specify the Giter8 version in project/build.properties file as:
giter8.version=0.12.0
3h 38m
This is part 2 of the post about sbt-projectmatrix, an experimental plugin that I’ve been working to improve the cross building in sbt. Here’s part 1. I’ve just released 0.4.0.
After adding sbt-projectmatrix to your build, here’s how you can set up a matrix with two Scala versions.
ThisBuild / organization := "com.example"
ThisBuild / scalaVersion := "2.12.10"
ThisBuild / version := "0.1.0-SNAPSHOT"
lazy val core = (projectMatrix in file("core"))
.settings(
name := "core"
)
.jvmPlatform(scalaVersions = Seq("2.12.10", "2.11.12"))
Read More…
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.
3h 8m
Released sbt 1.3.0.
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.
I gave a talk at Scala Days 2019 at Lausanne in June.
3h 4m
Last year I wrote an experimental sbt plugin called sbt-projectmatrix to improve the cross building in sbt. I’ve just released 0.2.0.
After adding sbt-projectmatrix to your build, here’s how you can set up a matrix with two Scala versions.
ThisBuild / organization := "com.example"
ThisBuild / scalaVersion := "2.12.8"
ThisBuild / version := "0.1.0-SNAPSHOT"
lazy val core = (projectMatrix in file("core"))
.settings(
name := "core"
)
.jvmPlatform(scalaVersions = Seq("2.12.8", "2.11.12"))
Read More…
git clone --no-hardlinks --branch master originalRepoURL childRepo
cd childRepo
git filter-branch --prune-empty --subdirectory-filter path/to/keep master
git remote remove origin
git prune
git gc --aggressive
Change originalRepoURL, master, and path/to/keep to appropriate values. Use -- --all to handle all branches.
In case you have multiple paths you want to filter, you need to use --index-filter together with GNU xargs and GNU sed available via brew install gnu-sed findutils.
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.
sdkman_auto_selfupdate to workaround the update prompt blocking the CI. Also it adds || true on the sdk install line.Here’s how we can use SDKMAN! on Travis CI to cross build using AdoptOpenJDK 11 and 8:
2h 58m
Ancillary Justice by Ann Leckie
My rating: 4 of 5 stars
‘Ancillary Justice’ is written in a first-person narrative as the AI of thousands of years old starship Justice of Toren of The Radchaai Empire. Another interesting part is since the Radchaai language is genderless, the narrator constantly describes everyone as “she,” but later you might discover that some character might be he. There are other small details here and there that narrator might say, but you start to question it as the story develops. In other words, Ann Leckie has done a stylish job of show-and-not-tell about the world that she’s built.
I wanted to run sbt inside Docker, so I created some images. The GitHub repo is eed3si9n/docker-sbt.
Over the holiday break I’ve implemented left TOC for Pamflet, and released it as Pamflet 0.8.0.
Pamflet is a publishing application for short texts, particularly user documentation of open-source software.
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.
3 h 28 min
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
Red Mars by Kim Stanley Robinson
My rating: 4 of 5 stars
Red Mars is a science fiction classic written in 1992. This book is everything I wanted and more, starting with first hundred astronauts and cosmonauts migrating to Mars to build the infrastructure such that more people can migrate. By the middle of the book, thousands of people migrate to Mars. The book explores various dimensions the epic project, not just technological challenges, but psychological effects, personality differences, and political interests by superpowers. The geography of Mars is written in vivid, majestic details.
I’ve implemented “super shell” feature for sbt over the weekend. The idea is to take over the bottom n lines of the termnial, and display the current tasks in progress.
Logs are useful in many situations, and sometimes it’s the only viable tool to find out what’s going on. But on a console app like sbt, using logs to tell the build user what’s going on doesn’t always work.
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",
"-language:experimental.macros",
"-language:higherKinds",
"-language:implicitConversions",
"-Ypartial-unification",
"-Yrangepos",
),
scalacOptions ++= (scalaVersion.value match {
case VersionNumber(Seq(2, 12, _*), _, _) =>
List("-Xfatal-warnings")
case _ => Nil
}),
Compile / console / scalacOptions --= Seq("-deprecation", "-Xfatal-warnings", "-Xlint")
)
lazy val foo = (project in file("foo"))
.settings(
commonSettings,
name := "foo",
)
Read More…
Working with GitHub and pull requests a lot, I end up accumulating stale branches that are no longer needed. In this post, we will look at how to clean the stale local branches.
There are mainly two strategies:
Erik Aybar’s Git Tip: Deleting Old Local Branches takes the second approach.
I’ve been thinking about rich console applications, the kind of apps that can display things graphically, not just appending lines at the end. Here are some info, enough parts to be able to write Tetris.
To display some text at an arbitrary location on a termial screen, we first need to understand what a terminal actually is. In the middle of 1960s, companies started selling minicomputers such as PDP-8, and later PDP-11 and VAX-11. These were of a size of a refrigerator, purchased by “computer labs”, and ran operating systems like RT-11 and the original UNIX system that supported up many simultaneous users (12 ~ hundreds?). The users connected to a minicomputer using a physical terminal that looks like a monochrome screen and a keyboard. The classic terminal is VT100 that was introduced in 1978 by DEC.
Whether you want to try using OpenJDK 11-ea, GraalVM, Eclipse OpenJ9, or you are stuck needing to build using OpenJDK 6, jabba has got it all. jabba is a cross-platform Java version manager written by Stanley Shyiko (@shyiko).
Here’s how we can use jabba on Travis CI to cross build using AdoptOpenJDK 8 and 11:
sudo: false
dist: trusty
group: stable
language: scala
scala:
- 2.12.7
env:
global:
- JABBA_HOME=/home/travis/.jabba
matrix:
include:
- env:
- TRAVIS_JDK=adopt@1.8.192-12
- env:
- TRAVIS_JDK=adopt@1.11.0-1
before_install:
- curl -sL https://raw.githubusercontent.com/shyiko/jabba/0.11.0/install.sh | bash && . ~/.jabba/jabba.sh
install:
- $JABBA_HOME/bin/jabba install $TRAVIS_JDK
- unset _JAVA_OPTIONS
- export JAVA_HOME="$JABBA_HOME/jdk/$TRAVIS_JDK" && export PATH="$JAVA_HOME/bin:$PATH" && java -Xmx32m -version
script: sbt -Dfile.encoding=UTF8 -J-XX:ReservedCodeCacheSize=256M ++$TRAVIS_SCALA_VERSION! test
before_cache:
- find $HOME/.ivy2 -name "ivydata-*.properties" -delete
- find $HOME/.sbt -name "*.lock" -delete
cache:
directories:
- $HOME/.ivy2/cache
- $HOME/.sbt/boot
- $HOME/.jabba/jdk
Read More…
Last week I wrote about using source dependencies with sbt-sriracha for testing purpose. This week we’ll look into using Expecty to do power assert.
Power assert (or power assertion) is a variant of assert(...) function that that prints out detailed error message automatically. It was originally implemented by Peter Niederwieser (@pniederw) for Spock, and in 2009 it was merged into Groovy 1.7. Power assert has spread to Ruby, JavaScript, Rust, etc.
Source dependencies is one of features that existed in sbt since ever, but hasn’t been documented well.
Here’s how to declare source dependency to the latest commit for scopt commandline option parsing library.
lazy val scoptJVMRef = ProjectRef(uri("git://github.com/scopt/scopt.git#c744bc48393e21092795059aa925fe50729fe62b"), "scoptJVM")
ThisBuild / organization := "com.example"
ThisBuild / scalaVersion := "2.12.2"
lazy val root = (project in file("."))
.dependsOn(scoptJVMRef)
.settings(
name := "Hello world"
)
Read More…
Yesterday I wrote about cross JVM testing using Travis CI.
Here’s how we can test Scala apps on macOS using Travis CI. This is adapted from Lars and Muuki’s method: Testing Scala programs with Travis CI on OS X
dist: trusty
language: scala
matrix:
include:
## build using JDK 8, test using JDK 8
- script:
- sbt universal:packageBin
- cd citest && ./test.sh
jdk: oraclejdk8
## build using JDK 8, test using JDK 8, on macOS
- script:
- sbt universal:packageBin
- cd citest && ./test.sh
## https://github.com/travis-ci/travis-ci/issues/2316
language: java
os: osx
osx_image: xcode9.2
## build using JDK 8, test using JDK 9
- script:
- sbt universal:packageBin
- jdk_switcher use oraclejdk9
- cd citest && ./test.sh
jdk: oraclejdk8
## build using JDK 8, test using JDK 10
- script:
- sbt universal:packageBin
- citest/install-jdk10.sh
- cd citest && ./test.sh
jdk: oraclejdk8
scala:
- 2.10.7
before_install:
# https://github.com/travis-ci/travis-ci/issues/8408
- unset _JAVA_OPTIONS
- if [[ "$TRAVIS_OS_NAME" = "osx" ]]; then
brew update;
brew install sbt;
fi
cache:
directories:
- $HOME/.ivy2/cache
- $HOME/.sbt/boot
before_cache:
- find $HOME/.ivy2 -name "ivydata-*.properties" -delete
- find $HOME/.sbt -name "*.lock" -delete
Read More…
Oracle is moving to ship non-LTS JDK every 6 months, and LTS JDK every 3 years. Also it’s converging to OpenJDK. In this scheme, JDK 9 will be EOL in March 2018; JDK 10 will come out in March 2018, and EOL in September 2018; and LTS JDK 11 that replaces JDK 8 in September 2018 will stay with us until 2021.
As we will see quick succession of JDKs in the upcoming months, here’s a how-to on testing your app on JDK 8, JDK 9, and JDK 10 Early Access using Travis CI.
During the SIP-27 trailing commas discussion, one of the thoughts that came to my mind was unifiying some of the commas with semicolons, and take advantage of the semicolon inference.
This doesn’t actually work. @Ichoran kindly pointed out an example:
As tweeted, I made some sbt stickers.
