No. All modules must be resolved for runtime. scala-compiler needs to be resolved to runtime and master. If you add master to anything else, they fail to resolve. And if you don't include runtime for scala-compiler, then the scala-library and scala-reflect jars don't end up being installed.  Why?  I don't know, I don't really understand what's going on here.  I've asked the SBT guys, we'll see what they say.