[plt-scheme] macro stepper enhancements

Ryan Culpepper wrote:
> On Oct 21, 2009, at 4:59 PM, Jon Rafkind wrote:
>
>> 1. I would like to hide a specific s-expression in the macro stepper. 
>> If I right click on a something, like letrec-values, and click 'hide' 
>> then all instances of letrec-values are hidden.
>
> Do you mean "hide" as the macro stepper uses the term, or do you mean 
> something more like "collapse s-expression"?
>

Yes, I meant collapse s-expression. That would be extremely useful 
considering the size of expanded terms.

>> 2. Going a step back takes a long time, I guess because the entire 
>> computation from beginning to end is re-computed? Can all the steps 
>> be cached along the way instead?
>
> They are. The steps are only recomputed when you change the hiding 
> policy. The time is being taken up by pretty-printing, coloring, 
> clickback-attaching, etc. I'll check to see if any of the latter parts 
> are happening outside of edit-sequences, but other than that I don't 
> know of any way to speed it up.
>

:( ok. For some of my expressions it takes upto 30 seconds.