https://github.com/clj-commons/virgil
Recompile Java code without restarting the REPL
https://github.com/clj-commons/virgil
clojure java javac repl
Last synced: 12 days ago
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Recompile Java code without restarting the REPL
- Host: GitHub
- URL: https://github.com/clj-commons/virgil
- Owner: clj-commons
- Created: 2015-11-19T05:27:19.000Z (over 9 years ago)
- Default Branch: master
- Last Pushed: 2025-03-27T21:35:22.000Z (28 days ago)
- Last Synced: 2025-04-05T19:07:32.516Z (19 days ago)
- Topics: clojure, java, javac, repl
- Language: Clojure
- Homepage:
- Size: 548 KB
- Stars: 327
- Watchers: 14
- Forks: 22
- Open Issues: 5
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Codeowners: .github/CODEOWNERS
Awesome Lists containing this project
README
Do you tarnish your Clojure with the occasional hint of Java? Have you become
indescribably tired of reloading your REPL every time you change anything with a
`.java` suffix? Look no further.
Virgil is a library for live-recompiling Java classes from the REPL. This can be
done either manually or by starting a process that watches your source
directories for changes in Java files and triggering recompilation when that
happens.
### Usage
Add `virgil/virgil` dependency to your `project.clj` or `deps.edn`. If you plan
to use Virgil just as a devtime dependency, then you probably want to add it to
a profile/alias which you enable only during development.
[](https://clojars.org/virgil/virgil)
```clj
(require 'virgil)
;; To recompile once, manually:
(virgil/compile-java ["src"])
;; To recompile automatically when files change:
(virgil/watch-and-recompile ["src"])
```
The main argument to these functions is a list of directories where Java source
files are located. Both functions can accept a list of string `:options` that is
passed to Java compiler, e.g. `:options ["-Xlint:all"]` to print compilation
warnings, and a `:verbose` flag to print all classnames that got compiled.
`watch-and-recompile` accepts an optional `:post-hook` function. You can use it
to, e.g., trigger `tools.namespace` refresh after the classes get recompiled.
Check [example](example) directory for a sample project.
Happy tarnishing.
### Can I use Virgil in production?
Virgil can compile Java classes at runtime in a production environment the same
way as it does during the development, so the answer is yes. However, when you
do a release build, it is advised to build real Java classes explicitly during
your build step using *javac* task of your build tool. There are multiple
arguments for it:
* You get extra reliability and assurance that the compiled Java classes will
be correctly discoverable by other code.
* You get one fewer runtime dependency.
* You won't have to rely on JDK-specific tools like `javax.tools` package that
might not be available in your production environment (e.g., if it runs on
JRE).
### Migration from 0.1.9
From version 0.3.0, Virgil no longer provides `lein-virgil` plugin for
Leiningen. Instead, you should add `virgil` as a regular dependency to your
project and call its functions from the REPL.
### Supported versions
Virgil makes sure to support Clojure 1.10+ and JDK 8, 11, 17, 21, 24 (see [CI
job](https://app.circleci.com/pipelines/github/clj-commons/virgil)). Supporting
future versions of Java so far required only bumping ASM library dependency, so
that shouldn't take long. Please, create an issue if you run into any
compatibility problems.
## Publishing new releases
Releases are handled by CircleCI. All you need to do is to tag a commit with a
`x.y.z` and push the tag.
### License
Copyright © 2016-2019 Zachary Tellman, 2022-2025 Oleksandr Yakushev
Distributed under the MIT License