On Sun, 23 Jul 2017 11:32:14 +0200,
Nicolas Goaziou wrote:
Hello

> 
> Hello,
> 
> "José L. Doménech" <domenechjosel@gmail.com> writes:
> 
> 
> Thank you. Some comments follow.
> 
> 
> :version "26.1"
> :package-version '(Org . "9.1")
>

Done.

> 
> (eq el '()) -> (null el)
>
Done.

> 
> The parenthesis needs to be moved at the end of the line above.
>

Done.

> Would you mind also providing an ORG-NEWS entry for that change?
>

No, but I don't know what is the preferred format for the entries. So
instead of a patch i send the complete entries.
Also I have not explain why I added the :prologue header. I think it is
general enough to be used in more creative ways than mine.

** New Features
*** Babel
***** Scheme: new variable: ~org-babel-scheme-null-to~

 This new custom option allows to use a empty list or null symbol to
 format the table output, initially assigned to 'hlines.

***** Scheme: new function: ~org-babel-scheme-table-or-string~
 
 New helper function to convert the return value from the scheme block
 to a table or a string.

***** Scheme: new header ~:prologue~

 A new block code header has been created for Org Babel that enables
 developers to prepend code to the scheme block being processed.

 Multiple =:prologue= headers can be added each of them using a string
 with the content to be added.

 The scheme blocks are prepared by surronding the code in the block
 with a let form. The content of the =:prologue= headers are prepended
 before this let form.

The Changelog entry:

Allows scheme code blocks to return a table and add a :prologue param
to the scheme blocks. All :prologue params are prepended to the
body of code.

* lisp/ob-scheme.el (org-babel-scheme-null-to): New custom option that
  allows to use a empty list or null symbol to format the table
  output, initially assigned to 'hlines.
  (org-babel-scheme-table-or-string): New helper function to convert
  the return value from the block to a table or a string.
  (org-babel-execute-src-block): Changed to allow the return of a
  table for the output.
  (org-babel-expand-body:scheme) Add :prologue param support.

A improved Changelog entry:

Allows scheme code blocks to return a table and add a :prologue param
to the scheme blocks. All :prologue params are prepended to the
body of code.

* lisp/ob-scheme.el (org-babel-scheme-null-to): New custom option that
  allows to use a empty list or null symbol to format the table
  output, initially assigned to 'hlines.
  (org-babel-scheme-table-or-string): New helper function to convert
  the return value from the block to a table or a string.
  (org-babel-execute-src-block): Changed to allow the return of a
  table for the output.
  (org-babel-expand-body:scheme) Add :prologue param support.

> Regards,
> 
> -- 
> Nicolas Goaziou

Thank you,

José L. Doménech

The modified patch: