Scala and Scala.js version included in artifact id

Question

I just successfully released my first Scala & Scala.js cross-building library to Sonatype and can now use the following two artifacts in my applicatons:

• https://search.maven.org/artifact/com.github.fbaierl/scala-tarjan_2.12/0.1.1/jar
• https://search.maven.org/artifact/com.github.fbaierl/scala-tarjan_sjs0.6_2.12/0.1.1/jar

My question now is: Why is the Scala and Scala.js version included in the artifact id? I don't think I have seen such a thing before so I was wondering if I did something wrong. Here is my build.sbt: https://github.com/fbaierl/scalajs-cross-compile-tarjan/blob/03954a3e2d1442ad339298a986209c1403c9692e/build.sbt

Answer 1

That's the way that Scala artifacts work. Pretty much all artifacts look like this -- it just isn't obvious when you use those artifacts in sbt, because (IIRC) the _2.12 is implied by the %% operator in sbt. (And the _sjs0.6 is implied by the %%% operator.)

The underlying reason for it is that artifacts compiled by different major versions of the Scala compiler (Scala versions are epoch.major.minor) aren't binary compatible (because otherwise the language and standard library couldn't evolve). You can't mix e.g. _2.12 and _2.11 artifacts on the classpath, so the “same” version of the same library must be published separately for both Scala versions, so the suffix is needed to distinguish them.