Yeah, the history thing added a lot of complexity for no compelling
benefit.  I'm not sure it's the best way to make a stepper anyway; it
might be simpler to add hooks to the expander as is done with stepping
the interpreter.

On Sun, Sep 20, 2009 at 8:32 AM, Taylor R Campbell <[email protected]> wrote:
>   Date: Sat, 19 Sep 2009 23:57:44 -0700
>   From: Chris Hanson <[email protected]>
>
>   OK, I'm done refactoring the syntax stuff.  Hopefully it's a little
>   easier to follow now.  I didn't make any major changes to the
>   syntaxing, just rearranged it to make the interfaces clearer and to
>   improve readability some.
>
> One major change you did make was to eliminate the history tracking.
> Although none of the system exploited this, and although there was
> some extra complexity in the bookkeeping for this, I often found it
> invaluable for debugging macros.  It would have been even nicer to
> teach the debugger about this so that we could have an expansion
> stepper like the one in DrScheme that I have heard people rave about.
>


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