Scala tool to remove all unused code

Question

I am writing a Scala plugin for an editor I use that would highlight all unused code paths (could be unused defs, vals, classes and implicits), and give the user an option to yank them out of the .scala file.

How can I do this? To simplify the problem, let's pretend we only have a single root level .scala file with no external dependency on libraries or any other code files.

Ideally I would want this to be an SBT plugin that, given a single such Foo.scala file, would spit out Foo_min.Scala file with all unused code removed.

Answer 1

Scalafix has a rewrite for this: RemoveUnusedImports

Follow those instructions to run it: https://scalacenter.github.io/scalafix/#Installation

Answer 2

You need some kind of semantic API to traverse over the code and ask questions like "is this variable/import ever used" ?

As far as I know, Intellij uses Meta programming System to achieve same goals. For scala, you can wait for scalameta's 2.0 release, which (most probably) will support semantic API.