[plt-scheme] Emacs modes and s-expression comments

From: Robby Findler (robby at cs.uchicago.edu)
Date: Thu Feb 16 18:25:52 EST 2006

At Thu, 16 Feb 2006 20:54:32 +0000, "Paulo J. Matos" wrote:
> Indeed, I started a thread some time ago exactly with that question in
> mind and he did tell me that he worked on it. I think the differences
> were obvious. The GUI improved a lot but obviously, we always want
> more! :)
> I've been thinking about the following, which I don't think it might
> be hard but I'm not that sure. How hard would it be to implement, as 
> tool,  an extra horizontal frame (like interactions for example) that
> would show up real-time documentation for what you are currently
> typing. Imagine you write "define", that would probably show you
> define syntax and maybe some comments on it.
> One of the difficulties would be to adjust the syntax shown to the
> language the user is using. The syntax for define probably shift a bit
> depending on the current language.
> Still, a first step would be to have a tool that at any moment is able
> to get what the user is typing. If it is in a cond expression, an if
> expression etc, so that a function can then be called to show doc
> about that.
> Any comments if this is useful, on any todo list, etc?
> Which difficulties would one have to face?

Sounds like a great idea. Most of the pieces are already there -- it
will be a question doing something good to avoid destroying

To create a new sub-window in DrScheme, see the tools manual to see how
to wire that window into an existing window. In particular, see

To see how to search in Help Desk, look at how the "f1" callback is
implemented in plt/collects/drscheme/private/rep.ss.

I think that you can start by queuing low-priority callbacks to handle
the searches and you'll want to be a little clever to avoid queuing
multiple callbacks at once -- just queue a single callback and use
`set!' to change what the callback is going to do, once it gets
serviced. If that takes away from interactivity too much, see how the
online syntax coloring works. It is much more sophisticated, tho. Maybe
some abstraction can be built from it, tho.

Good luck.


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