sbt 1.3.12


I'm happy to announce sbt 1.3.12 patch release. Full release note is here -

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.

Change since sbt 1.3.11

There was a regression in sbt 1.3.11 around the launcher integration, which showed up as repositories file getting ignored. sbt 1.3.12 fixes it. #5583

sbt 1.3.11


Update: There was a regression in sbt 1.3.11. Please use 1.3.12 instead.

Jar Jar Abrams


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.

Selective functor in sbt


Selective functor can facilitate conditional execution of tasks while keeping the ability to run inspect command.

Selective composition can be implemented in sbt as Def.taskIf macro:

Def.taskIf {
  if (Boolean) something1
  else something2

keeping promise in sbt


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.


cached compilation for sbt


The notion of cached compilation or remote cache has been around for a while now, but often it required the setup has not been easy. If we can bake build-as-function feature into basic tool chain such as Zinc and sbt, Scala community in general can benefit from it to speed up the build.

Even for open source projects, if Travis CI publishes into Bintray or something, the contributors might be able to resume compilation off of the last build.

The PR for sbt change is sbt/sbt#5534, and the virtualization change in Zinc is sbt/zinc#712.

about me

I am Eugene Yokota (@eed3si9n on Twitter and GitHub), a software engineer with years of experience working on Scala tooling. I've been lead sbt maintainer since 2014, former Tech Lead of the Lightbend Tooling Team, and Principal Engineer on the Scala (Compiler) Team (See 6 years at Lightbend for details). I'm passionate about improving developer experience on and off the work, and like to tinker with ideas both through coding and this blog as my personal platform.

sbt 1.3.10


I'm happy to announce sbt 1.3.10 patch release. Full release note is here -

Normally changing the project/ to


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.

Zinc 1.4.0-M1


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.

parallel cross building, part 3


sbt-projectmatrix 0.4.0 came pretty close, but there are some issue I ran into when I tried to use it in a real project. First is the lack of % syntax.

It's fairly common for subprojects to depend only from Test configuration, or depend on Compile from Compile, and Test from Test. 0.5.0 adds % to make this possible.

lazy val app = (projectMatrix in file("app"))
  .dependsOn(core % "compile->compile;test->test")
    name := "app"
  .jvmPlatform(scalaVersions = Seq("2.12.10"))
lazy val core = (projectMatrix in file("core"))
    name := "core"
  .jvmPlatform(scalaVersions = Seq("2.12.10", "2.13.1"))

Another feature that's available to Project is .configure(...) method. It takes a vararg of Project => Project functions, and applies them in order. Since some of the builds I deal with uses .configure(...) this helps me migrate from Project to ProjectMatrix.

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