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AFAIK, the CoffeeScript guys are working intensely on it. To some extent, any language which has accurate source position information in its parser/AST, and uses Closure Compiler on the backend can get source map output almost for free.

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Yea I would imagine they are. I haven't been following the development like I used to, so thanks.

How accurate does the source position information have to be? I don't think the CoffeeScript lexer can output column numbers (at least it didn't last time I checked) and the re-writing stage might give them a little trouble. Should be doable though.

Guess I should head over to github and see how they're doing and start reading the SourceMap spec.

Here's a link to the CoffeeScript discussion on source maps (with a working alternate solution).

https://github.com/jashkenas/coffee-script/issues/558

IIRC, you only need line number and filename. The map is JS <startline/startcol> -> Source <line,filename>

However, you can embed extra metadata for your specific source language if you wish, via the extension mechanism. Debug tools can then read the metadata in to do extra neat kinds of mapping (such as collapsing "native" stack frames).

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