ClojureScript source maps

[John]

Is there any interest in having ClojureScript generate source maps?

http://code.google.com/p/closure-compiler/wiki/SourceMaps

There are a couple of ways to accomplish this.

[David Nolen]

I'm sure there is a considerable amount of interest in this.

David 

[Brandon Bloom]

SourceMap support is rapidly approaching general availability in Chrome and Firefox:

http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/

I'd love to see this happen and *may* be able to find time to help with implementation.

Any intel on existing attempts at this?

[David Nolen]

There are no existing attempts. The first step would be just to get the compiler to emit an optional source map. Bonus points if we can merge source maps from the ClojureScript compiler and Closure advanced compilation.

David

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[Brandon Bloom]

> The first step would be just to get the compiler to emit an optional source map.

That's definitely the first step! After that, there's going to need to be some way to serve those source maps via HTTP upon request from the browser.

However, there's a first step to the first step: Getting column data. The reader currently seems to only produce a :line key in the metadata map.

> Bonus points if we can merge source maps from the ClojureScript compiler and Closure advanced compilation.

Could you please clarify? Do you mean for multi-level mapping?

See the "Multi-level Mapping Notes" section in the v3 spec:

https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit?hl=en_US&pli=1&pli=1

It seems like once they agree upon a header (as opposed to the javascript comment syntax) this would also be useful for providing pre-macro-expansion vs post-macro-expansion source maps.

[David Nolen]

On Fri, Mar 23, 2012 at 10:51 PM, Brandon Bloom <snpr...@gmail.com> wrote:

> The first step would be just to get the compiler to emit an optional source map.

That's definitely the first step! After that, there's going to need to be some way to serve those source maps via HTTP upon request from the browser.

However, there's a first step to the first step: Getting column data. The reader currently seems to only produce a :line key in the metadata map.

Yep. This would require enhancing the Clojure reader. I don't think that's feasible for 1.4, but probably worth pursuing for 1.5. Even without it, we can still get line level debugging which is better than nothing and write the code to use :column data when available.

 

Could you please clarify? Do you mean for multi-level mapping?

Yes. Again this is really just bonus points. Priority 1 is just improving the development experience.

 

See the "Multi-level Mapping Notes" section in the v3 spec:

https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit?hl=en_US&pli=1&pli=1

It seems like once they agree upon a header (as opposed to the javascript comment syntax) this would also be useful for providing pre-macro-expansion vs post-macro-expansion source maps.

 We could also decide to handle multi-mapping ourselves - that is write the code that can produce a merged source map.

David

[Brandon Bloom]

 We could also decide to handle multi-mapping ourselves - that is write the code that can produce a merged source map.

It seems likely (already done?) for browsers to support the X-SourceMap header and //@ comments for the target use case of CoffeeScript -> Javascript -> Minified Javascript

Also, it seems preferable to let the browser do it, so their debugger can operate at various levels of source translation depending on your needs.

So why bother doing it ourselves? For the Rhino environment?

[Sean Allen]

On Sun, Jul 24, 2011 at 1:19 PM, John <conca...@gmail.com> wrote:

Lots of interest from me.