Re: We have asynchronous sessions, why have anything else?

[Tom Gillespie]

> I am not even sure if all the babel backends support try-except.
> Think about ob-gnuplot or, say, ob-latex.

Indeed many do not. Defining some standard "features"
for org babel language implementations is something that
is definitely of interest so that we can provide clear interfaces
for things like stdio, error handling, return values, async,
file output, remote execution, sessions, return value caching,
module discovery/tangling, execution from file vs stdin, execution
without a file system path, runtime environment specification,
and much more. However, at the moment there is only a preliminary
survey of a subset of these that was put together by Ian Martins.

https://orgmode.org/worg/org-contrib/babel/languages/lang-compat.html

> the two could be unified if we expand the functionality of the async filter

While this might be possible, I would definitely hold off on this because
the changes in semantics absolutely will break many users' blocks. We
barely knew what the impact of changing the default return value for shell
blocks would be.

I absolutely look forward to the day when this can be done safely and
with confidence, but I think we need a much stronger handle on babel
interfaces in general before such a change could even be considered.

At the moment each ob lang impl pretty much has to be considered
to be completely unique, even if the text looks like bash for e.g.
shell, comint, and screen. Users are known to rely on undocumented
quirks of the ob lang impls that can differ wildly in their semantics.

Best!
Tom