This fork is a work-in-progress branch to change the Livescript compiler's output from JS text to the Parser API AST, which can then be further optimized/analyzed, or generated back to JS text with escodegen. This gets us about halfway to source maps, at the cost of further deviation from the CoffeeScript/coco codebases while still falling short of full CoffeeScriptRedux.

I've been working on it on and off for the past months. I felt it time to at least stick it on github publicly, so other interested parties can potentially help/comment.

• Fix label compilation
• Fix reuse of temporary variables.
• Somehow retain JS comments in AST output.

While you can run the unit tests with slake, it's easier at this point to just compare the compiled output until it's identical.

There are two included tools for this purpose, regen.ls and tast.ls. Use them with your favorite diff program (I like meld) like so (using zsh's incredibly helpful temporary file substitution syntax):

TEST=test/label.ls
meld =(lsc -cbp $TEST | lsc regen.ls) =(lsc -aj $TEST | lsc tast.ls) 

This takes the stable version's output, passes it through esprima/escodegen to take out any trivial formatting differences, and compares it with the new compilation using ast.ls in the src/ directory (which takes the LiveScript AST as input and outputs Parser API ast, then puts it through escodegen).

If the files are identical, they should compile to the same text. If not, it should be easier to tell where the new compiler went wrong.

If the new compiler bails out completely with an error, you can inspect the generated JS AST by passing an extra argument to tast:

lsc -aj $TEST | lsc tast.ls give-me-the-ast

If there is JS ast that is mistakenly toStringed by the old codegen, it should show up as a string in a weird place.

Thus, the feedback loop is:

1. Run meld on a test file
2. Fix src/ast.ls
3. GOTO 1 unless file is fixed
4. If every test file compiles identically, run slake build and see if the whole compiler recompiles. If it does, you're done!

In some ways, I feel like this is the wrong way to go, and we should instead just scrap the ad-hoc compiler for a CSR-based design. In other ways though, the old compiler is still pretty nice, and "going halfway" will still kind-of-allow bug fixes to propagate from old coco and coffeescript.

However, in the process, I've unraveled some of the ultra-compact code from coco and added comments, which might be helpful regardless.

is a language which compiles to JavaScript. It has a straightforward mapping to JavaScript and allows you to write expressive code devoid of repetitive boilerplate. While LiveScript adds many features to assist in functional style programming, it also has many improvements for object oriented and imperative programming.

Check out livescript.net for more information, examples, usage, and a language reference.

Have Node.js installed. sudo npm install -g LiveScript

After, run livescript for more information.

git://github.com/gkz/LiveScript.git