[racket] getting symbol documentation URL quickly within Emacs

Forgot to mention: I could also use quick-reference information of 
procedure/macro syntax/args in Emacs, for displaying in echo area or 
tooltip as you're editing a use of the procedure/macro.

So, how the quick-reference gets implemented might influence how getting 
the URL for more documentation gets implemented.

Neil Van Dyke wrote at 06/25/2011 04:13 AM:
> If I'm in Emacs, and I have a symbol for some Racket standard library 
> procedure or syntax, and I want to get the URL (or open the URL in 
> browser) for the documentation for that symbol... what is a good and 
> fast way to do that?
>
> Ideas I've considered so far:
>
> 1. Use "racket/help".  I don't want to do this, since I'd really 
> prefer not to keep a "racket" process open for this purpose, and 
> invoking "racket" each time is uncomfortably slow.  (As the below 
> timings show, the "help" macro is not very fast: on my 2GHz dual-core 
> (with no swap), when the pertinent files *are* cached by Linux, 
> getting the URL takes about 2.6 seconds.  When caches are empty except 
> for what is needed to start the "racket" process, getting the URL 
> takes about 15.6 seconds.  Looking up *subsequent* symbols in the same 
> "racket" process takes only around 0.2 seconds, however.)
>
> 2. Keep a "racket" process open and use some lookup of my own design.  
> I'm guessing this is the same as "racket/help", and so I have the same 
> objections.
>
> 3. Have Emacs find the appropriate "index.html" on the filesystem or 
> on "racket-lang.org", and then send a URL to that with the "q" query 
> parameter for my symbol, letting the JS look up the documentation, and 
> waiting for the JS the first time.  This will at least get me a list 
> of search hits, but won't jump to the documentation for the exact symbol.
>
> 4. Have Emacs load the documentation indexes (perhaps in the 
> background when idle, at startup, and when we notice they change) and 
> do the lookup in Emacs.  This is what Quack did for older PLT 
> documentation, and it stopped working when the documentation format 
> changed and I didn't have time to rewrite.  I could also be sensitive 
> about things like which "#lang" we were in (like I could with an 
> external process, if I passed it the  "#lang" information).
>
> Any more ideas/thoughts?  (Other than pressing me on why I'd rather 
> not keep a "racket" process open for this purpose.  Eventually the new 
> Emacs mode, Meow, will probably do that for things like Check Syntax, 
> but I don't want to go there yet if I don't have to.)
>
> Note that all these require some notion of *from which Racket install 
> tree or which Racket version on the Web do you want this 
> documentation*, and that's some HCI and coding work that has to be 
> done in any case.
>
> ---- BEGIN ----
> ~  echo 3 | sudo tee /proc/sys/vm/drop_caches
> 3
> ~  echo '(display "hello, world!\n")' | racket
> Welcome to Racket v5.1.1.
> > hello, world!
> >
> ~  time echo "(help begin)" | racket
> Welcome to Racket v5.1.1.
> > Loading help index...
> Sending to web browser...
>  file: /usr/local/racket-5.1.1/share/racket/doc/reference/begin.html
>  anchor: (form._((quote._~23~25kernel)._begin))
> Starting Firefox...
> >
>
> real    0m15.584s
> user    0m2.472s
> sys    0m0.180s
> ~  time echo "(help begin)" | racket
> Welcome to Racket v5.1.1.
> > Loading help index...
> Sending to web browser...
>  file: /usr/local/racket-5.1.1/share/racket/doc/reference/begin.html
>  anchor: (form._((quote._~23~25kernel)._begin))
> Starting Firefox...
> >
>
> real    0m2.622s
> user    0m2.240s
> sys    0m0.124s
> ~ time echo "(begin (help and) (help or))" | racket
> Welcome to Racket v5.1.1.
> > Loading help index...
> Sending to web browser...
>  file: /usr/local/racket-5.1.1/share/racket/doc/reference/if.html
>  anchor: (form._((lib._racket/private/letstx-scheme..rkt)._and))
> Starting Firefox...
> Sending to web browser...
>  file: /usr/local/racket-5.1.1/share/racket/doc/reference/if.html
>  anchor: (form._((lib._racket/private/letstx-scheme..rkt)._or))
> Starting Firefox...
> >
>
> real    0m2.858s
> user    0m2.216s
> sys    0m0.116s
> ~ ---- END ----
>