jua

Jua is a lua interpreter implemented in java.

It features a CLI (repl + interpreter for files) and a web application.

You can access the web application here (disclaimer it won't work in https because it's using heroku's free tier).

Installation

Requirements:

• Java 11 or later
• Gradle 5 or later

OR

• docker

SDKMAN! is a good solution to install and manage Gradle, Java SDK, etc...

Setup

Clone the project:

git clone git@github.com:jua-cs/jua.git

Usage

To build jua you can run:

./gradlew assemble

This will build a jar in ./build/libs/jua-0.0.0.jar

that you can run doing:

java -jar ./build/libs/jua-0.0.0.jar --help (this will prompt you the help of the Jua CLI)

REPL

To launch a lua REPL you can just do: java -jar build/libs/jua-0.0.0.jar

It will prompt you with a REPL where you can write lua code and it will be lexed, parsed and evaluated on the fly.

File execution

To execute a specific file you can do: java -jar build/libs/jua-0.0.0.jar <my_file.lua>, for instance: java -jar build/libs/jua-0.0.0.jar ./src/test/java/jua/evaluator/testdata/bool.lua

This will execute the given lua file directly and exit shortly after.

Execution API

To launch the web server only you can do: java -jar build/libs/jua-0.0.0.jar --server, this will start it on port 3000 by default (you can configure it using the PORT env variable).

You can then try it with: curl -XPOST -H 'Content-Type: application/json' -d '{"code": "print(100 * 5)"}' http://localhost:3000/api/v1/interpreter.

If you have yarn and nodejs installed you can also run the web UI (or access it here) to access this API by execution the start-front-dev script located in the scripts directory.

Debug

There is also a -d, --debug flag that allows you to log what's happening during the different steps (lexing, parsing and evaluation)

Tooling

To setup the pre-commit hooks (checks for linting of both the backend and the frontend) you can run:

./gradlew installGitHooks

You can also use the scripts in ./scripts

• start-front-dev starts the frontend in development mode

Docker

You can also run the whole stack using docker or podman:

docker build . -t jua && docker run -p 127.0.0.1:3000:3000 jua

Then just launch your favorite browser and head to http://localhost:3000/ to execute some lua.

Documentation

Look a the more comprehensive documention here !

Possible Improvements

• Add support for unicode
• Better stack traces
• Implement coroutines
• Implement require to be able to import libraries
• Implement the remaining builtins, and the missing features
• Improve performances (10x difference for fibonacci computation compared to the official lua implementation)
• Add a code formatter (it could use the AST to do that)
• Allow to share lua snippets in the web UI