ErlyJS is a Javascript compiler running on and compiling for the Erlang virtual machine.

Motivation:

• Short answer: For highly scalable and lightning fast serverside Javascript.
• Long answer: The ultimate goal is to simplify the process of building Ajax and Comet Web applications. ErlyJS should help to achieve this by allowing the same programming language for server and client side. There is not much choice for that programming language, Javascript is the only one running natively in web browsers. To run Javascript at serverside there are existing solutions (Rhino, Spidermonkey) but for better horizontal scalability, performance, fault tolerance and ease of deployment, the multi-core and high-concurrency Erlang virtual machine has been chosen and a Javascript compiler had to be developed from scratch. ErlyJS should provide full interoperability with Erlang, so web frameworks and Web / Application servers written in Erlang can be used.

Implementation details:

• Leex/Yecc based grammar
• Compiler generates byte code for the Erlang VM
• Option: recompilation only if source has changed (compiled Javascript modules store source checksum)

Compatibility:

• Javascript version: 1.5
• Spidermonkey/Rhino: global function load

Project status:

Pre-alpha. Right now a major refactoring is taking place to move the code base from erl_syntax based approach to Core Erlang. The code in SVN trunk is out of date, git is used now and repo URLs will be announced here once the refactoring to Erlang Core is complete

ToDo:

• Add all the missing stuff to provide full Javascript support, comparable to Spidermonkey and Rhino
• Implement native serverside Browser DOM support
• Implement AST parse transformations for:
• pretty-printing Javascript source code
• safely shrinking Javascript source code
• refactoring Javascript source code
• Implement API for Javascript debugging, profiling and code analysis

Wanna contribute ?

• You are familiar with Erlang, Javascript, Lambda Calculus, Parsers and Lexers: you are the most wanted !
• You know Javascript, but not Erlang: write Javascript tests