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Bali

Bali is a WIP JavaScript engine written in Nim that aims to be as compliant as possible to the ECMAScript specifications.
Bali is still not in a usable state yet and is probably unstable. It is not meant to be used in production for now.

I repeat,

Bali is still not in a usable state yet and is probably unstable. It is not meant to be used in production for now.

Usage

Whilst not a "real-world usage", Bali is integrated into the Ferus web engine and used as the JavaScript runtime's primary execution backend.

Contact Me

You can join the Ferus Discord Server to discuss Bali and other components of the Ferus web engine.

Specification Compliance

As of 9th of November, 2024, Bali can successfully run 35% of the entire Test262 suite* (I believe that our test runner is broken, but that's what it currently tells me about the number of passing tests). There's a lot of work to be done here, so don't shy away from sending in PRs. ;)

Running code with Bali

You can compile Balde, the Bali debugger by running:

$ nimble build balde

It is primarily used for debugging the engine as of right now, but it runs code fine too.

Integrating Bali into your applications

Again, Bali is not in a usable state yet. However, it is possible to use Bali in your programs. There is no easy Nim-to-JS conversion layer yet, most of the JS code that calls Nim is using a lot of hacks and bridges provided by Mirage.
Balde requires the C++ backend to be used as it depends on simdutf!

Firstly, add Bali to your project's dependencies.

$ nimble add gh:ferus-web/bali

Here is a basic example of the API:

import bali/grammar/prelude
import bali/runtime/prelude

const JS_SRC = """
console.log("Hello world!")
console.log(13 + 37)

var myUrl = new URL("https://github.com/ferus-web/bali")
console.warn(myUrl.origin)

var commitsToBali = 171
while (commitsToBali < 2000) {
    commitsToBali++
    console.log(commitsToBali)
}

let lemonade = fetchLemonade(4)
console.log(lemonade)
"""

let 
  parser = newParser(JS_SRC) # Feed your JavaScript code to Bali's JavaScript parser
  ast = parser.parse() # Parse an AST out of the tokens
  runtime = newRuntime("myfile.js", ast) # Instantiate the JavaScript runtime.

# define a native function which is exposed to the JavaScript code
runtime.defineFn(
    "fetchLemonade",
    proc =
      let num = runtime.ToNumber(&runtime.argument(1))

      if num == 0 or num > 1:
        ret str("You have " & $num & " lemonades!")
      else:
        ret str("You have a lemonade!")
)

# Emit Mirage bytecode and pass over control to the Mirage VM.
# NOTE: This is a blocking function and will block this thread until execution is completed (or an error is encountered and the
# interpreter is halted)
runtime.run()

Roadmap

  • Getting a grammar to AST parser [X]
  • Getting the MIR emitter working [X]
  • Get arithmetic operations working [X]
  • Console API [X]
  • While loops [X]
  • Nested object field access [X]
  • typeof [X]
  • Arrays [ ]
  • For loops [ ]
  • Modules [ ]
  • Async [ ]