Re: Backtrace and enhanced catch

[Kevin Ryde]

Neil Jerram <address@hidden> writes:
>
> The spec for catch's pre-unwind-handler would be that it can exit
> either normally or non-locally.  If it exits normally, Guile unwinds
> (dynamic context + stack) and then calls the normal (post-unwind)
> handler.  If it exits non-locally, that exit determines the
> continuation.

Hmm.  Now my head hurts.  I'm not so sure what I want any more (apart
from a reliable backtrace).

> But if we want to be ultra-cautious we could keep lazy-catch as it
> is and introduce `with-pre-unwind-handler' (or something) with the
> proposed semantics.

Better be pretty strictly compatible, it's hairy enough without
changing between guile versions.