Re: R6RS exception printing at the REPL

[Andreas Rottmann <a.rottmann@gmx.at>]

Andy Wingo <wingo@pobox.com> writes:

> On Sun 24 Oct 2010 23:46, Andreas Rottmann <a.rottmann@gmx.at> writes:
>
>> Attached is a patch that improves the way R6RS exceptions are printed at
>> the REPL
>
> Cool! I have also found the need to define pretty-printers for various
> throw keys. I wonder, could you rework this patch to add a more generic
> exception-printing mechanism?
>
Sure, that would make sense, and I can then also squash all the
occurances where exceptions are printed that I've missed in the last
patch.

> I'm going to display my ignorance in public and try to write down some
> types. := is a type definition, and : declares the type of something.
>
>   exception-printer := port args -> nothing
>
>   set-exception-printer! : exception-printer -> nothing
>
Did you mean the following?

set-exception-printer! : key exception-printer -> nothing

>   exception-printer : key -> exception-printer
>
>   print-exception : key args port -> nothing
>
> The default behavior could be hard-coded into print-exception. The first
> two procedures (set-exception-printer!, exception-printer, and
> print-exception) could go into boot-9, and the third into (system repl
> error-handling), or a new module under ice-9.
>
Sorry, I don't understand this -- there are three procedures, which you
all say should go into boot-9.scm?  Or did you mean that
`print-exception' should go into `(system repl error-handling)'?

> What do you think?
>
Besides the above questions, I wonder where I should install the
exception printer for R6RS exceptions (since the code will depend on
quite a bit of R6RS, so we maybe want to have it loaded on demand, like
in the last patch.

Regards, Rotty
-- 
Andreas Rottmann -- <http://rotty.yi.org/>