Bug: Empty result when Emacs Lisp code block evals to nil [9.0.5 (release_9.0.5-401-g86ff11 @ /Users/xcy/src/org-mode/lisp/)]

Bug: Empty result when Emacs Lisp code block evals to nil [9.0.5 (release_9.0.5-401-g86ff11 @ /Users/xcy/src/org-mode/lisp/)]

[Chunyang Xu]

Hi.

I notice that if the result is nil during executing emacs-lisp code
block, org simply displays a empty #+RESULT block. For example,


#+BEGIN_SRC emacs-lisp
t
#+END_SRC

#+RESULTS:
: t

#+BEGIN_SRC emacs-lisp
nil
#+END_SRC

#+RESULTS:


I don't see why 'nil' is special than other values like 't'.


--
Emacs  : GNU Emacs 26.0.50 (build 10, x86_64-apple-darwin16.4.0, NS appkit-1504.81 Version 10.12.3 (Build 16D32))
 of 2017-03-28
Package: Org mode version 9.0.5 (release_9.0.5-401-g86ff11 @ /Users/xcy/src/org-mode/lisp/)

Re: Bug: Empty result when Emacs Lisp code block evals to nil [9.0.5 (release_9.0.5-401-g86ff11 @ /Users/xcy/src/org-mode/lisp/)]

[Nicolas Goaziou]

Chunyang Xu <mail@xuchunyang.me> writes:

> I notice that if the result is nil during executing emacs-lisp code
> block, org simply displays a empty #+RESULT block. For example,
>
> #+BEGIN_SRC emacs-lisp
> t
> #+END_SRC
>
>
> #+RESULTS: : t
>
> #+BEGIN_SRC emacs-lisp
> nil
> #+END_SRC
>
> #+RESULTS:
>
>
> I don't see why 'nil' is special than other values like 't'.

It is special because it is also how code evaluation specifies that
there is no produced output.

You may want to use :results scalar, e.g.,

  #+BEGIN_SRC emacs-lisp :results scalar
  nil
  #+END_SRC

  #+RESULTS:
  : nil

Regards,

-- 
Nicolas Goaziou