+
+(defvar org-babel-scheme-repl-map (make-hash-table :test 'equal)
+ "Map of scheme sessions to session names.")
+
+(defun org-babel-scheme-cleanse-repl-map ()
+ "Remove dead buffers from the REPL map."
+ (maphash
+ (lambda (x y)
+ (when (not (buffer-name y))
+ (remhash x org-babel-scheme-repl-map)))
+ org-babel-scheme-repl-map))
+
+(defun org-babel-scheme-get-session-buffer (session-name)
+ "Look up the scheme buffer for a session; return nil if it doesn't exist."
+ (org-babel-scheme-cleanse-repl-map) ; Prune dead sessions
+ (gethash session-name org-babel-scheme-repl-map))
+
+(defun org-babel-scheme-set-session-buffer (session-name buffer)
+ "Record the scheme buffer used for a given session."
+ (puthash session-name buffer org-babel-scheme-repl-map))
+
+(defun org-babel-scheme-get-buffer-impl (buffer)
+ "Returns the scheme implementation geiser associates with the buffer."
+ (with-current-buffer (set-buffer buffer)
+ geiser-impl--implementation))
+
+(defun org-babel-scheme-get-repl (impl name)
+ "Switch to a scheme REPL, creating it if it doesn't exist:"
+ (let ((buffer (org-babel-scheme-get-session-buffer name)))
+ (or buffer
+ (progn
+ (run-geiser impl)
+ (if name
+ (progn
+ (rename-buffer name t)
+ (org-babel-scheme-set-session-buffer name (current-buffer))))
+ (current-buffer)))))
+
+(defun org-babel-scheme-make-session-name (buffer name impl)
+ "Generate a name for the session buffer.
+
+For a named session, the buffer name will be the session name.
+
+If the session is unnamed (nil), generate a name.
+
+If the session is `none', use nil for the session name, and
+org-babel-scheme-execute-with-geiser will use a temporary session."
+ (let ((result
+ (cond ((not name)
+ (concat buffer " " (symbol-name impl) " REPL"))
+ ((string= name "none") nil)
+ (name))))
+ result))
+
+(defun org-babel-scheme-execute-with-geiser (code output impl repl)
+ "Execute code in specified REPL. If the REPL doesn't exist, create it
+using the given scheme implementation.
+
+Returns the output of executing the code if the output parameter
+is true; otherwise returns the last value."
+ (let ((result nil))
+ (with-temp-buffer
+ (insert (format ";; -*- geiser-scheme-implementation: %s -*-" impl))
+ (newline)
+ (insert (if output
+ (format "(with-output-to-string (lambda () %s))" code)
+ code))
+ (geiser-mode)
+ (let ((repl-buffer (save-current-buffer
+ (org-babel-scheme-get-repl impl repl))))
+ (when (not (eq impl (org-babel-scheme-get-buffer-impl
+ (current-buffer))))
+ (message "Implementation mismatch: %s (%s) %s (%s)" impl (symbolp impl)
+ (org-babel-scheme-get-buffer-impl (current-buffer))
+ (symbolp (org-babel-scheme-get-buffer-impl
+ (current-buffer)))))
+ (setq geiser-repl--repl repl-buffer)
+ (setq geiser-impl--implementation nil)
+ (geiser-eval-region (point-min) (point-max))
+ (setq result
+ (if (equal (substring (current-message) 0 3) "=> ")
+ (replace-regexp-in-string "^=> " "" (current-message))
+ "\"An error occurred.\""))
+ (when (not repl)
+ (save-current-buffer (set-buffer repl-buffer)
+ (geiser-repl-exit))
+ (set-process-query-on-exit-flag (get-buffer-process repl-buffer) nil)
+ (kill-buffer repl-buffer))
+ (setq result (if (or (string= result "#<void>")
+ (string= result "#<unspecified>"))
+ nil
+ (read result)))))
+ result))
+