Re: `lazy-catch' and `dynamic-wind'

[Ludovic Courtès]

Hi Neil,

"Neil Jerram" <address@hidden> writes:

> This is as expected.  Note that there is nothing like dynamic-wind
> inside fluid-set!  Did you perhaps mean with-fluids instead?  If you
> used with-fluids, I would expect the same behaviour as you've
> described for parameterize.

Yes, that comparison to native fluids was inappropriate.

> That text is misleading and should be improved.  See the manual
> section [1] for the whole story, which explains that it is actually
> only the call stack that is not unwound.
>
> [1] 
> http://www.gnu.org/software/guile/manual/html_node/Lazy-Catch.html#Lazy-Catch
>
> This is why I invented with-throw-handler and the optional
> pre-unwind-handler parameter of `catch'.  Perhaps you need to use one
> of those instead.

Exactly, thanks!  Now, I was actually using SRFI-34's
`with-exception-handler', which I expected to behave like
`with-throw-handler'.  Should we change `with-exception-handler' to use
`with-throw-handler' instead of `lazy-catch'?

(In fact, I don't understand when the `lazy-catch' semantics could be
preferable over the `with-throw-handler' semantics'.)

Thanks,
Ludo'.