[plt-scheme] Where is macroexpand in PLT Scheme?

From: John Clements (clements at brinckerhoff.org)
Date: Tue Nov 11 21:45:54 EST 2003

On Tuesday, Nov 11, 2003, at 21:27 US/Eastern, Robby Findler wrote:

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> At Tue, 11 Nov 2003 17:21:20 -0800 (PST), Bill Clementson wrote:
>> It seems odd that it always shows up as colorer.ss or
>> #f. Maybe it is getting confused somewhere and is
>> using the filename of the last editor object that was
>> used (in this case, the syntax colorer?)?
> No DrScheme's got it right, I think. All of your source is either some
> unknown place or the definitions window.

I think it confuses some folks that references to the definitions 
window contain the letters "colorer.ss".

If (like I was) you are confused, here's what's going on:

MzScheme provides a powerful 'mixin' facility; at runtime, a mixin 
applied to a class yields a class.  This facility is used widely to 
extend DrScheme's functionality.  That is, to extend the 'DrScheme 
definitions text% class', you supply a mixin that can be composed with 
that class.  Instances of the resulting class are assigned the source 
position of the last applied mixin.

So, references to the definitions-text% show up as strings containing a 
reference to the file containing the last-mixed-in tool.

FWIW, for a long time the stepper was the last-mixed-in tool.  This led 
to lots of finger-pointing from the uninitiated.


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