How to compile just some files with sbt?

Question

I've come pretty well along with sbt, the Scala Build Tool. If you only have small problems in the code, it's easy.

Now, after a major feature add, much of my code is broken and I sbt seems to be confused as to how the dependencies are. I could help it, compiling the fundamental modules first, but it does not seem to let me.

It's help system is... notorious.

> help compile
Compiles sources.

Yeah, well. I guessed that.

What I wanted to hear was: how do I compile only - say - src/module/A.scala.

This might not even be possible (hello again, make, never abandoned you!). At least I cannot find any reference on the Internet to applying sbt compile just to a single file.

I'm using sbt from the command line prompt, not an IDE.

UPDATE:

It was my fault. :/ Had split a source file into multiple, but forgot to copy a package clause to each of the new ones. Oooops.

Will keep this open for a while, since compiling just a single file (i.e. something like sbt compile filename) would imho not be a bad thing.

Answer 1

You could define a Multi-Project Build where the files you want to compile separately are encapsulated in a project. According to the docs, the following is then possible:

At the sbt interactive prompt, type projects to list your projects and project to select a current project. When you run a task like compile, it runs on the current project. So you don't necessarily have to compile the root project, you could compile only a subproject.