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This is where the code for the Ammonite project lives; Both:

If you want to learn more about Ammonite or how to use it, check out the links above, or ask on the Gitter Channel. The remainder of this document is developer-docs for people who want to work on the Ammonite source code itself.

If you are interested in living more "on the edge", we also publish artifacts and the doc-site every commit; the doc-site is available at

And contains instructions on how to download the per-commit executable or depend on the perf-commit maven artifact.

Developer Docs

The layout of the repository is roughly:

  • ops/ is Ammonite-Ops
  • amm/ is Ammonite's core, REPL and script runner
  • shell/ is Ammonite-Shell
  • terminal/ is the JLine re-implementation used by Ammonite-REPL to provide syntax highlighting and multiline editing
  • readme/ is the source code for the Documentation, written in Scalatex.
  • published/ is a synthetic project used for publishing, excluding the readme and integration tests

For more detailed information, check out the internals documentation for high-level overviews of some facets of the codebase

Common Commands

Manual Testing

Although most features should be unit tested, it's still useful to fire up a REPL from the current codebase to see things work (or not). There are a variety of shells you can spin up for testing different things:

  • sbt ~terminal/test:run is useful for manual testing the terminal interaction; it basically contains a minimal echo-anything terminal, with multiline input based on the count of open- and closed-parentheses. This lets you test all terminal interactions without all the complexity of the Scala compiler, classloaders, etc. that comes in repl/
  • sbt ~amm/test:run brings up the Ammonite-REPL using the source code in the repository, and automatically restarts it on-exit if you have made a change to the code. Useful for manual testing both of amm/ as well as ops/, since you can just import ammonite.ops._ and start using them. Note that this does not bring in filesystem utilities like the wd variable, cd! command. You can also pass in the path to a .sc file to run it using Ammonite's script runner
  • sbt ~shell/test:run brings up a fully-loaded shell with all filesystem utilities included: wd, cd!, autocomplete for filesystem paths, and more. This uses readme/resources/example-predef.scala instead of your default predef, for easier experimentation and development.
  • sbt ~integration/test:run runs the trivial main method in the integration subproject, letting you manually test running Ammonite programmatically, whether through run or debug
  • sbt ~integration/test:console brings up a console in the integration subproject, loading Ammonite-REPL as a test console, as described in the readme. Similar to integration/test:run but useful for verifying the different classloader/execution environment we get by starting Ammonite inside the Scala REPL doesn't break things
  • sbt ~amm/test:assembly creates an assembly at amm/target/scala-2.11/amm that you

Automated Testing

While working on a arbitrary xyz subproject, sbt ~xyz/test runs tests after every change. amm/test can be a bit slow because of the amount of code it compiles, so you may want to specify the test manually via amm/test-only --

  • ops/test tests the filesystem operations, without any REPL present
  • amm/test tests the Ammonite-REPL/Script-runner, without filesystem-shell integration.
  • terminal/test tests the readline re-implementation: keyboard navigation, shortcuts, editing, without any filesystem/scala-repl logic
  • shell/test tests the integration between the standalone ops/ and amm/ projects: features like cd!/wd, path-completion, ops-related pretty-printing and tools
  • integration/test kicks off the integration tests, which bundle amm/ and shell/ into their respective jars and invoke them as subprocesses. Somewhat slow, but exercises all the command-line-parsing stuff that the other unit tests do not exercise, and makes sure that everything works when run from .jars instead of loose class-files


  • Publishing is automatic, controlled by scripts in the ci/ folder.

  • Every commit that lands in master will publish a new unstable version, that you can already use and download. This includes publishing the unstable version to maven central to the snapshot-commit-uploads tag, and updating the documentation-site so it's Unstable Version download instructions to point to it, though the "main" download/install instructions in the doc-site will not be changed.

  • Every commit that lands in master with a tag will re-publish a stable version to maven central and upload a new versioned release (using the tag as the version) and the doc-site is updated so the main download/install instructions point at the new published stable version.

In general, if you land a change in master, once CI completes (1-2hrs) you should be able to download it via the Unstable Version instructions and make use of your changes standalone or in an SBT project.

Occasionally, the CI job building and publishing one of the above steps flakes and fails, and needs to be re-run through the travis web interface.

Issue Tags

I've started tagging open issues in the issue tracker to try and keep things neat. This is what the various tags mean:

Each issue should only have one of these:

  • bug: this behavior clearly wrong, and needs to be fixed
  • enhancement: something relatively speccable, that can be worked on, finished, and will make Ammonite better
  • wishlist: could be totally awesome, but we're uncertain if it is worth doing at all, what it would look like, or if it will ever reach a "finished" state.

And possibly:

  • help wanted: I don't have context, hardware, or for some other reason am unlikely to ever do this. But I know people out there care, so one of you should step up and fix it.

Contribution Guidelines

  • All code PRs should come with: a meaningful description, inline-comments for important things, unit tests (positive and negative), and a green build in CI
  • Try to keep lines below 80 characters width, with a hard limit of 100 characters.
  • PRs for features should generally come with something added to the Documentation, so people can discover that it exists
  • Be prepared to discuss/argue-for your changes if you want them merged! You will probably need to refactor so your changes fit into the larger codebase
  • If your code is hard to unit test, and you don't want to unit test it, that's ok. But be prepared to argue why that's the case!
  • It's entirely possible your changes won't be merged, or will get ripped out later. This is also the case for my changes, as the Author!
  • Even a rejected/reverted PR is valuable! It helps explore the solution space, and know what works and what doesn't. For every line in the repo, at least three lines were tried, committed, and reverted/refactored, and more than 10 were tried without committing.
  • Feel free to send Proof-Of-Concept PRs that you don't intend to get merged.