Re: [O] Bug: Problems with ob-scheme in geiser-eval--retort-output [9.2.6 (9.2.6-4-ge30905-elpa @ /home/lockywolf/.emacs.d/elpa/org-20191021/)]

[Vladimir Nikishkin]

On 21/10/2019 23:24, Vladimir Nikishkin wrote:
> Well, checking for "output" doesn't seem to be useful any way, since
> "output" is never 'nil.
> 
> Regarding the fact that the error should be reported to the geiser
> mailing list, that's entirely true. The problem is that the person who
> would be responsible for this error would be me. :) At least for the
> chibi-scheme part.
> 
> I don't think that having a few extra checks on the org/geiser interface
> is bad, especially there is also comint coming into play. I can imagine
> valid reasons when "output" is not a valid serialized scheme expression.
> 
> On 21/10/2019 22:46, Neil Jerram wrote:
>> On Mon, 21 Oct 2019 at 15:16, Vladimir Nikishkin <address@hidden
>> <mailto:address@hidden>> wrote:
>>
>>     Yeah. The "output" is not the result of geiser's elisp functions, as far
>>     as I understand, it comes from comint, which reads it from a scheme
>>     interpreter, and is expected to be formatted specifically to be fed into
>>     geiser-eval--retort-output by the geiser scheme functions (running
>>     inside a scheme interpreter).
>>
>>     So "output" is never 'nil, because comint, when scheme produces some
>>     rubbish, just makes it an empty string, which is not 'nil.
>>
>>     Then, "output" is expected to be "retorted" back from a serialized
>>     scheme expression into an elisp expression by
>>     geiser-eval--retort-output. And this actually may and produce a 'nil,
>>     but there is no check for it.
>>
>>     So, again, both of the geiser steps (namely, (a) serializing a sexp in
>>     scheme, and (b) de-serializing it in geiser-eval--retort-output) may
>>     fail.
>>
>>
>> I agree that it's fragile for geiser/scheme to output a sexp that it
>> hopes geiser/elisp will be able to read back.  (I'm guilty of doing that
>> in the past too!)
>>
>> Do you have a specific example of that?  It feels like the right thing
>> to do would be to report that to the Geiser list, as this could and
>> should be fixed entirely within the Geiser code.
>>   
>>
>>
>>     Yes, I have seen this going on, actually quite a lot, because both
>>     geiser and different scheme interpreters are in constant development and
>>     get broken every other day.
>>
>>
>> I use Org with Guile 2.2.3 (via Geiser), and it seems a pretty stable
>> setup to me.
>>  
>> Best wishes,
>>      Neil
>>  


A particularl example could be, perhaps, when an interpreter crashes and
produces something like "Segmentation fault", which is not a valid
geiser-sexp.

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