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Experimental utilities for dealing with "the classpath", and dynamically loading libraries.

Blog post: The Classpath is a Lie

With thanks to Nextjournal!

Nextjournal provided the incentive and financial support to dive into this. Many thanks to them for pushing to move the needle on dev experience.


Watch deps.edn

(require '[ :as watch-deps])

(watch-deps/start! {:aliases [:dev :test]})

Whenever you change deps.edn this will pick up any extra libraries or changed versions, and add them to the classpath.

Caveat: we can only add to the classpath, any dependencies that were present when the app started will remain accessible.

You can pass the option :include-local-roots? true to also watch any deps.edn of projects that are referenced via :local/root in your project's deps.edn

Classpath inspection and manipulation

(require '[lambdaisland.classpath :as licp])

Get the current chain of classloaders


Also see which entries each loader searches


Update a gitlib in deps.edn to the latest :git/sha in main or in the specified :git/branch

(licp/git-pull-lib 'com.lambdaisland/ornament)

Add/override the classpath based on the current deps.edn.

  '{:aliases [:dev :test :licp]
    :extra {:deps {com.lambdaisland/webstuff {:local/root "/home/arne/github/lambdaisland/webstuff"}}}})

Access specific class loaders


Lambda Island Open Source


classpath is part of a growing collection of quality Clojure libraries created and maintained by the fine folks at Gaiwan.

Pay it forward by becoming a backer on our Open Collective, so that we may continue to enjoy a thriving Clojure ecosystem.

You can find an overview of our projects at lambdaisland/open-source.




Everyone has a right to submit patches to classpath, and thus become a contributor.

Contributors MUST

  • adhere to the LambdaIsland Clojure Style Guide
  • write patches that solve a problem. Start by stating the problem, then supply a minimal solution. *
  • agree to license their contributions as MPL 2.0.
  • not break the contract with downstream consumers. **
  • not break the tests.

Contributors SHOULD

  • update the CHANGELOG and README.
  • add tests for new functionality.

If you submit a pull request that adheres to these rules, then it will almost certainly be merged immediately. However some things may require more consideration. If you add new dependencies, or significantly increase the API surface, then we need to decide if these changes are in line with the project's goals. In this case you can start by writing a pitch, and collecting feedback on it.

* This goes for features too, a feature needs to solve a problem. State the problem it solves, then supply a minimal solution.

** As long as this project has not seen a public release (i.e. is not on Clojars) we may still consider making breaking changes, if there is consensus that the changes are justified.


Copyright © 2021 Arne Brasseur and Contributors

Licensed under the term of the Mozilla Public License 2.0, see LICENSE.

Can you improve this documentation? These fine people already did:
Arne Brasseur & Burin Choomnuan
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