From f6c09411a7a295230f8c033e54aadab14adf71e8 Mon Sep 17 00:00:00 2001
From: Eric Schulte <schulte.eric@gmail.com>
Date: Fri, 27 Aug 2010 18:01:24 -0600
Subject: [PATCH] ob-scheme: very preliminary support for evaluating scheme
 code blocks

* Makefile (LISPF): adding ob-scheme.el to the makefile
* lisp/ob-scheme.el: very preliminary support for evaluating scheme
  code blocks
* lisp/org.el (org-babel-load-languages): adding scheme
---
 Makefile          |  3 +-
 lisp/ob-scheme.el | 97 +++++++++++++++++++++++++++++++++++++++++++++++
 lisp/org.el       |  1 +
 3 files changed, 100 insertions(+), 1 deletion(-)
 create mode 100644 lisp/ob-scheme.el

diff --git a/Makefile b/Makefile
index ec22eefae..1c1f31756 100644
--- a/Makefile
+++ b/Makefile
@@ -150,7 +150,8 @@ LISPF      = 	org.el			\
 		ob-screen.el		\
 		ob-plantuml.el		\
 		ob-org.el		\
-		ob-js.el
+		ob-js.el		\
+		ob-scheme.el
 
 LISPFILES0  = $(LISPF:%=lisp/%)
 LISPFILES   = $(LISPFILES0) lisp/org-install.el
diff --git a/lisp/ob-scheme.el b/lisp/ob-scheme.el
new file mode 100644
index 000000000..452a940ec
--- /dev/null
+++ b/lisp/ob-scheme.el
@@ -0,0 +1,97 @@
+;;; ob-scheme.el --- org-babel functions for Scheme
+
+;; Copyright (C) 2010 Free Software Foundation
+
+;; Author: Eric Schulte
+;; Keywords: literate programming, reproducible research, scheme
+;; Homepage: http://orgmode.org
+;; Version: 0.01
+
+;;; License:
+
+;; This program is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 3, or (at your option)
+;; any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING.  If not, write to the
+;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+;; Boston, MA 02110-1301, USA.
+
+;;; Commentary:
+
+;; Now working with SBCL for both session and external evaluation.
+;;
+;; This certainly isn't optimally robust, but it seems to be working
+;; for the basic use cases.
+
+;;; Requirements:
+
+;; - a working scheme implementation
+;;   (e.g. guile http://www.gnu.org/software/guile/guile.html)
+
+;;; Code:
+(require 'ob)
+(require 'ob-eval)
+
+(defvar org-babel-default-header-args:scheme '()
+  "Default header arguments for scheme code blocks.")
+
+(defcustom org-babel-scheme-cmd "guile"
+  "Name of command used to evaluate scheme blocks."
+  :group 'org-babel
+  :type 'string)
+
+(defun org-babel-expand-body:scheme (body params &optional processed-params)
+  "Expand BODY according to PARAMS, return the expanded body."
+  (let ((vars (nth 1 (or processed-params (org-babel-process-params params)))))
+    (if (> (length vars) 0)
+        (concat "(let ("
+                (mapconcat
+                 (lambda (var) (format "%S" (print `(,(car var) ',(cdr var)))))
+                 vars "\n      ")
+                ")\n" body ")")
+      body)))
+
+(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'"
+  (let* ((processed-params (org-babel-process-params params))
+	 (session (not (string= (nth 0 processed-params) "none")))
+         (result-type (nth 3 processed-params))
+         (full-body (org-babel-expand-body:scheme body params processed-params)))
+    (read
+     (if session
+         ;; session evaluation
+         (error "Scheme sessions are not yet supported.")
+       ;; external evaluation
+       (let ((script-file (org-babel-temp-file "lisp-script-")))
+         (with-temp-file script-file
+           (insert
+            ;; return the value or the output
+            (if (string= result-type "value")
+                (format "(display %s)" full-body)
+              full-body)))
+         (org-babel-eval
+	  (format "%s %s" org-babel-scheme-cmd script-file) ""))))))
+
+(defun org-babel-prep-session:scheme (session params)
+  "Prepare SESSION according to the header arguments specified in PARAMS."
+  (error "not yet implemented"))
+
+(defun org-babel-scheme-initiate-session (&optional session)
+  "If there is not a current inferior-process-buffer in SESSION
+then create.  Return the initialized session."
+  (error "Scheme sessions are not yet supported."))
+
+(provide 'ob-scheme)
+
+;; arch-tag: 6b2fe76f-4b25-4e87-ad1c-225b2f282a71
+
+;;; ob-scheme.el ends here
diff --git a/lisp/org.el b/lisp/org.el
index 39c78860b..d85a1702d 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -167,6 +167,7 @@ requirements) is loaded."
 		 (const :tag "Python" python)
 		 (const :tag "Ruby" ruby)
 		 (const :tag "Sass" sass)
+		 (const :tag "Scheme" scheme)
 		 (const :tag "Screen" screen)
 		 (const :tag "Shell Script" sh)
 		 (const :tag "Sql" sql)