Re: org-babel interpreter prompts

[Dan Davison <davison@stats.ox.ac.uk>]

Rick Moynihan <rick.moynihan@gmail.com> writes:

> Hi all,
>
> I'm wondering if it's possible to get org-babel to output the
> interpreter prompts and sessions, as if each expression in the src
> block had been entered into the repl... e.g. something like:
>
> #+begin_src ruby :output repl
> 10 + 10
> puts "hello world"
> [1,2,3,4,5,6,7,8,9,10].map do |i|
>   i * i
> end
> #+end_src
>
> Yielding:
>
> #+results
> : irb(main):001:0> 10 + 10
> : => 20
> : irb(main):002:0> puts "Hello World"
> : Hello World
> : => nil
> : irb(main):003:0> [1,2,3,4,5,6,7,8,9,10].map do |i|
> : irb(main):004:1*   i * i
> : irb(main):005:1> end
> : => [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
> : irb(main):006:0>
>
> The rational for this is that it lets you provide examples of being at
> the prompt and write better documentation.  I'd imagine that in this
> mode, you wouldn't want the original src block to be rendered, rather
> just the output as if it had been run interactively.
>
> I'd personally find this useful and would like to see this for ruby,
> shell and clojure modes...  Though it'd be nice to have it work for
> all the other languages and modes that support a REPL or interactive
> prompt too.

Hi Rick,

I believe this should be possible when using :session by altering the
code that processes the output from the comint buffer. I had a quick
attempt at hacking that and failed, as Eric's code in that area is quite
sophisticated for me. (I still don't get how to debug macros.) So over
to Eric.

Note that when not using :session, this effect may still be possible on
a language-by-language basis. For example, with R we can control this
with arguments to the R executable:

~> echo '4+4' | R --vanilla
> 4+4
[1] 8
> 
~> echo '4+4' | R --vanilla --slave
[1] 8
~> 

and so a simple change to org-babel-R.el could introduce user control
over this when using external process evaluation (a.o.t. session).

I don't know whether ruby has something similar. For shell I'm also not
sure. There's bash -x, but that's not quite the same.

So perhaps we could introduce variables called something like
org-babel-ruby-args and org-babel-R-args so that the user can specify
these command line args to external interpreters.

Dan