Re: Debugging support in Eclipse?

Dominique Boucher <[email protected]> writes:

> Do you think it would be possible to implement a graphical debugger on
> top of that? I mean, given a continuation, can I produce the
> equivalent of a stack trace, traverse it and display the local
> variables names/values and such? Or does the SISC implementation make
> this impossible? Where should I look for hints?

It is possible to implement something like this, but it is quite a lot
of work and there are some serious conceptual difficulties due to tail
calls.


We do get fairly reasonable stack traces these days, if one is running
with maxStackTraceDepth set to a non-zero value. However, I doubt the
stack traces fit Eclipse's notion of a stack trace - they are
"compressed" in order to deal with tail calls. We could of course
unfold them but then they can become very long indeed; just think of a
tail recursive loop over a 1000 element long list.

The first extension of this would be to keep track of the call
parameters. The difficulties with that are that it prevents stack trace
compression since the args in tail-recursive loop will typically differ
from call to call. It also breaks safe-for-space-ness.

Keeping track of the lexical params suffers from similar problems. Plus
we'd need to keep track of some kind of param -> name mapping, since
all lexical params are kept in flattened arrays.

All of the above should be done in plain SISC first before integrating
with eclipse.


Matthias.



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