I hope it will be useful for someone.

José L. Doménech

On Sun, 16 Jul 2017 19:08:02 +0200,
José L. Doménech wrote:
> 
> [1  <text/plain; US-ASCII (7bit)>]
> Hello, I have modified 'ob-scheme.el' to be able to return org tables.
> 
> This is a quick patch. I hope you find it useful buut I could modify,
> document or write test for it if necesary.
> 
> I have already assigned the copyright for Emacs to the FSF.
> 
> 
> Enhance the scheme babel block output.
> 
> Allow scheme code blocks to return a table.
> 
> * lisp/ob-scheme.el (org-babel-scheme-null-to): New custom option that
>   allows to use a empty list 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 as a table or a string.
>   (org-babel-execute-src-block): Changed to allow the return of a table for
>   the output.
> 
> [2 ob-scheme.el.diff <text/plain; US-ASCII (base64)>]
> 1 file changed, 35 insertions(+), 11 deletions(-)
> lisp/ob-scheme.el | 46 +++++++++++++++++++++++++++++++++++-----------
> 
> modified   lisp/ob-scheme.el
> @@ -51,6 +51,13 @@
>                    (start end &optional and-go raw nomsg))
>  (declare-function geiser-repl-exit "ext:geiser-repl" (&optional arg))
>  
> +(defcustom org-babel-scheme-null-to 'hline
> +  "Replace `null' in scheme tables with this before returning."
> +  :group 'org-babel
> +  :version "24.4"
> +  :package-version '(Org . "8.0")
> +  :type 'symbol)
> +
>  (defvar org-babel-default-header-args:scheme '()
>    "Default header arguments for scheme code blocks.")
>  
> @@ -176,6 +183,18 @@ is true; otherwise returns the last value."
>  		       result))))
>      result))
>  
> +(defun org-babel-scheme-table-or-string (results)
> +  "Convert RESULTS into an appropriate elisp value.
> +If the results look like a list or tuple, then convert them into an
> +Emacs-lisp table, otherwise return the results as a string."
> +  (let ((res (org-babel-script-escape results)))
> +    (if (listp res)
> +        (mapcar (lambda (el) (if (or (eq el '()) (eq el 'null))
> +				 org-babel-scheme-null-to
> +			       el))
> +                res)
> +      res)))
> +
>  (defun org-babel-execute:scheme (body params)
>    "Execute a block of Scheme code with org-babel.
>  This function is called by `org-babel-execute-src-block'"
> @@ -184,7 +203,6 @@ This function is called by `org-babel-execute-src-block'"
>  			      "^ ?\\*\\([^*]+\\)\\*" "\\1"
>  			      (buffer-name source-buffer))))
>      (save-excursion
> -      (org-babel-reassemble-table
>         (let* ((result-type (cdr (assq :result-type params)))
>  	      (impl (or (when (cdr (assq :scheme params))
>  			  (intern (cdr (assq :scheme params))))
> @@ -192,16 +210,22 @@ This function is called by `org-babel-execute-src-block'"
>  			(car geiser-active-implementations)))
>  	      (session (org-babel-scheme-make-session-name
>  			source-buffer-name (cdr (assq :session params)) impl))
> -	      (full-body (org-babel-expand-body:scheme body params)))
> -	 (org-babel-scheme-execute-with-geiser
> -	  full-body			 ; code
> -	  (string= result-type "output") ; output?
> -	  impl				 ; implementation
> -	  (and (not (string= session "none")) session))) ; session
> -       (org-babel-pick-name (cdr (assq :colname-names params))
> -			    (cdr (assq :colnames params)))
> -       (org-babel-pick-name (cdr (assq :rowname-names params))
> -			    (cdr (assq :rownames params)))))))
> +	      (full-body (org-babel-expand-body:scheme body params))
> +	      (result
> +	       (org-babel-scheme-execute-with-geiser
> +		full-body			 ; code
> +		(string= result-type "output")   ; output?
> +		impl				 ; implementation
> +		(and (not (string= session "none")) session))) ; session
> +	      )
> +	 (let ((table
> +		(org-babel-reassemble-table
> +		 result
> +		 (org-babel-pick-name (cdr (assq :colname-names params))
> +				      (cdr (assq :colnames params)))
> +		 (org-babel-pick-name (cdr (assq :rowname-names params))
> +				      (cdr (assq :rownames params))))))
> +	   (org-babel-scheme-table-or-string table))))))
>  
>  (provide 'ob-scheme)
>  
> [3  <text/plain; ISO-8859-1 (quoted-printable)>]
> 
> 
> Best regards:
> 
> José L. Doménech