Fwd: Breakpoints, stepping forwards?

[Nicholas Papadonis]



Does anyone have information on how to use the stepper in MIT Scheme?  It’s my understanding it’s not documented.

Thanks


Begin forwarded message:

From: Nicholas Papadonis <address@hidden>
Date: March 27, 2020 at 11:42:17 EDT
To: Chris Hanson <address@hidden>, address@hidden
Subject: Re:  Breakpoints, stepping forwards?

This was helpful and you answered my question.  Does anyone have an example on how to use the stepper?

src/edwin/eystep.scm

shows the interface, however there is no documentation.   The keys do not work inside the debugger after a breakpoint, so I’m assuming the stepper is used differently than the (bkpt) system.  If anyone can provide a small use case that is appreciated.

On Mar 27, 2020, at 3:56 AM, Chris Hanson <address@hidden> wrote:

I’m not sure exactly what you’re asking about.

The debugger can’t examine what will happen in the future, because that hasn’t happened yet.

If you want to move forward, you have several options:

1. Resume the program using one of the restarts that are shown when you stop.
2. Evaluate subexpressions in the debugger to see what they do.
3. Run the stepper to evaluate expressions one step at a time.

The stepper isn’t documented but the source files are runtime/ystep.scm for the basic stepper and edwin/eystep.scm for the Edwin stepper interface.  Caveats: the stepper works only for interpreted code, not compiled code, so you can’t step into compiled code to see what it’s doing.

On Mar 26, 2020, 5:20 PM -0700, Nicholas Papadonis <address@hidden>, wrote:

When I insert (bkpt) in the code it launches the debugger, it appears the debugger can move backwards in subproblems/reductions, however cannot move forward past the (bkpt).

Is there a way to evaluate expressions forward past the break point?

I did not see an option in the debugger help. 

Thanks