added first cut preferences

original commit: e0602b131696404ed25ec79b12f8df83bde7ebac

collects/mred/prefs.ss

@@ -1,3 +1,5 @@
+;; need a preference for pconvert
+
 (define mred:preferences@
   (unit/s mred:preferences^
     (import [mred:debug mred:debug^]
@@ -16,20 +18,39 @@
 	(hash-table-get preferences p
 			(lambda () 
 			  (raise (mred:exn:make-exn:unknown-preference
-				  (format "unknown preference: ~a" p)))))))
+				  (format "unknown preference: ~a" p)
+				  ((debug-info-handler))))))))
 
     (define set-preference
       (lambda (p value) (hash-table-put! preferences p value)))
 
-    (define defaults '((highlight-parens #t)))
+    (define defaults '((highlight-parens #t)
+		       (autosaving-on? #t)
+		       (autosave-delay 60)
+		       (autoload-paths ("/usr/local/lib/plt/mred/autoload/"))))
 
     (define restore-defaults
       (lambda ()
 	(for-each (lambda (x) (apply set-preference x)) 
 		  defaults)))
 
-    (define save-user-preferences (lambda () (mred:debug:printf "saving prefs~n")))
-    (define read-user-preferences (lambda () (mred:debug:printf "reading prefs~n")))
+    (define save-user-preferences 
+      (lambda () 
+	(call-with-output-file preferences-filename
+	  (lambda (p) (write (hash-table-map preferences list) p))
+	  'replace)))
+
+    (define read-user-preferences 
+      (lambda ()
+	(when (file-exists? preferences-filename)
+	  (for-each (lambda (x) (apply set-preference x))
+		    (call-with-input-file preferences-filename read)))))
+
+    (define preferences-dialog
+      (lambda () 
+	(restore-defaults)
+	(save-user-preferences)
+	(wx:message-box "Saved default preferences.")))
     
     (restore-defaults)
     (read-user-preferences)))