[racket] match and debug in Advanced Student

On Nov 8, 2011, at 8:17 PM, Prabhakar Ragde wrote:

> I never use the Debug button, but I let my students start using Advanced Student today, and of course they tried it out.
> 
> The following program induces a strange error when the Debug button is pressed.
> 
> (match 3
>  [`(,x) 3]
>  [x 3])
> 
> The error is:
> internal error: skipped binding is used
> 
> after which the program hangs, though it can be stopped with the Stop button. --PR

This is partly speculation, but my guess here is that the debugger's annotation (which was forked from the stepper's annotation many years ago) has not been kept in sync with changes to the language. In particular, I'm pretty certain that the phrase "skipped binding is used" is mine. In the stepper, certain bindings 

...

here, lemme look.

Whoops! 

No, it looks like that comes from "resolve.c", and to me that suggests a bug in racket. I take it this is reproducible?

John

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