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Differences with Clojure

Babashka is implemented using the Small Clojure Interpreter. This means that a snippet or script is not compiled to JVM bytecode, but executed form by form by a runtime which implements a substantial subset of Clojure. Babashka is compiled to a native binary using GraalVM. It comes with a selection of built-in namespaces and functions from Clojure and other useful libraries. The data types (numbers, strings, persistent collections) are the same. Multi-threading is supported (pmap, future).

Differences with Clojure:

  • A pre-selected set of Java classes are supported. You cannot add Java classes at runtime.

  • Interpretation comes with overhead. Therefore loops are slower than in Clojure on the JVM. In general interpretation yields slower programs than compiled programs.

  • No deftype, definterface and unboxed math.

  • defprotocol and defrecord are implemented using multimethods and regular maps. Ostensibly they work the same, but under the hood there are no Java classes that correspond to them.

  • Currently reify works only for one class at a time

  • The clojure.core.async/go macro is not (yet) supported. For compatibility it currently maps to clojure.core.async/thread. More info here.

Libraries, pods and projects

A list of projects (scripts, libraries, pods and tools) known to work with babashka.

Pods

Pods are programs that can be used as a Clojure library by babashka. Documentation is available in the library repo.

Package babashka script as a AWS Lambda

AWS Lambda runtime doesn’t support signals, therefore babashka has to disable handling of SIGINT and SIGPIPE. This can be done by setting BABASHKA_DISABLE_SIGNAL_HANDLERS to true.

Articles, podcasts and videos

Including new libraries or classes

Before new libraries or classes go into the standardly distributed babashka binary, these evaluation criteria are considered:

  • The library or class is useful for general purpose scripting.

  • Adding the library or class would make babashka more compatible with Clojure libraries relevant to scripting.

  • The library cannot be interpreted by with babashka using --classpath.

  • The functionality can’t be met by shelling out to another CLI or can’t be written as a small layer over an existing CLI (like babashka.curl) instead.

  • The library cannot be implemented a pod.

If not all of the criteria are met, but adding a feature is still useful to a particular company or niche, adding it behind a feature flag is still a possibility. This is currently the case for next.jdbc and the PostgresQL and HSQLDB database drivers. Companies interested in these features can compile an instance of babashka for their internal use. Companies are also free to make forks of babashka and include their own internal libraries. If their customized babashka is interesting to share with the world, they are free to distribute it using a different binary name (like bb-sql, bb-docker, bb-yourcompany, etc.). See the feature flag documentation and the implementation of the existing feature flags (example commit).

Babashka book

In the future we will migrate examples from this README to the babashka book. This is work in progress and you are welcome to contribute.

Related projects

Thanks

Contributors

Code Contributors

This project exists thanks to all the people who contribute. [Contribute].

Financial Contributors

Become a financial contributor and help us sustain our community.

Individuals

Organizations

Support this project with your organization. Your logo will show up here with a link to your website.

License

Copyright © 2019-2020 Michiel Borkent

Distributed under the EPL License. See LICENSE.

This project contains code from:

  • Clojure, which is licensed under the same EPL License.