Index: /trunk/ccl/level-1/l1-streams.lisp
===================================================================
--- /trunk/ccl/level-1/l1-streams.lisp	(revision 4892)
+++ /trunk/ccl/level-1/l1-streams.lisp	(revision 4893)
@@ -31,6 +31,5 @@
 
 (defclass stream ()
-  ((direction :initarg :direction :initform nil :reader stream-direction)
-   (closed :initform nil)))
+  ())
 
 (defclass input-stream (stream)
@@ -38,4 +37,18 @@
 
 (defclass output-stream (stream) ())
+
+(defmethod stream-direction ((s stream))
+  )
+
+(defmethod stream-direction ((s input-stream))
+  (if (typep s 'output-stream)
+    :io
+    :input))
+
+(defmethod stream-direction ((s output-stream))
+  (if (typep s 'input-stream)
+    :io
+    :output))
+
 
 ;;; The "direction" argument only helps us dispatch on two-way streams:
@@ -224,10 +237,4 @@
 				 (%strerror error-number) context)))
 
-(defmethod initialize-instance :after ((stream input-stream) &key)
-  (let ((direction (slot-value stream 'direction)))
-    (if (null direction)
-      (set-slot-value stream 'direction :input)
-      (if (eq direction :output)
-        (set-slot-value stream 'direction :io)))))
 
 
@@ -278,5 +285,5 @@
 
 (defmethod open-stream-p ((stream stream))
-  (not (slot-value stream 'closed)))
+  t)
 
 (defmethod stream-fresh-line ((stream output-stream))
@@ -353,9 +360,25 @@
   (dirty nil)
   (outbuf-lock nil)
-  (owner nil))
+  (owner nil)
+  (read-char-function 'ioblock-no-char-input)
+  (read-byte-function 'ioblock-no-binary-input)
+  (write-char-function 'ioblock-no-char-output)
+  (write-byte-function 'ioblock-no-binary-output))
 
 
 ;;; Functions on ioblocks.  So far, we aren't saying anything
 ;;; about how streams use them.
+
+(defun ioblock-no-binary-input (ioblock)
+  (report-bad-arg (ioblock-stream ioblock) '(and binary-stream input-stream)))
+
+(defun ioblock-no-binary-output (ioblock)
+  (report-bad-arg (ioblock-stream ioblock) '(and binary-stream output-stream)))
+
+(defun ioblock-no-character-input (ioblock)
+  (report-bad-arg (ioblock-stream ioblock) '(and character-stream input-stream)))
+
+(defun ioblock-no-character-output (ioblock)
+  (report-bad-arg (ioblock-stream ioblock) '(and character-stream output-stream)))
 
 
@@ -1052,5 +1075,11 @@
   (typep s 'fundamental-input-stream))
 
-(defclass fundamental-character-stream (fundamental-stream)
+(defclass binary-stream (stream)
+    ())
+
+(defclass character-stream (stream)
+    ())
+
+(defclass fundamental-character-stream (fundamental-stream character-stream)
     ())
 
@@ -1058,9 +1087,13 @@
   'character)
 
-(defclass fundamental-binary-stream (fundamental-stream)
+(defclass fundamental-binary-stream (fundamental-stream binary-stream)
     ())
 
+(defclass character-input-stream (input-stream character-stream)
+    ())
+
 (defclass fundamental-character-input-stream (fundamental-input-stream
-                                              fundamental-character-stream)
+                                              fundamental-character-stream
+                                              character-input-stream)
     ())
 
@@ -1086,23 +1119,32 @@
   (generic-read-line s))
 
+(defclass character-output-stream (output-stream character-stream)
+    ())
+
 (defclass fundamental-character-output-stream (fundamental-output-stream
-                                               fundamental-character-stream)
+                                               fundamental-character-stream
+                                               character-output-stream)
     ())
 
+(defclass binary-input-stream (input-stream binary-stream)
+    ())
+
 (defclass fundamental-binary-input-stream (fundamental-input-stream
-                                           fundamental-binary-stream)
+                                           fundamental-binary-stream
+                                           binary-input-stream)
     ())
 
 (defclass fundamental-binary-output-stream (fundamental-output-stream
-                                            fundamental-binary-stream)
+                                            fundamental-binary-stream
+                                            binary-output-stream)
     ())
 
 
 (defmethod stream-read-byte ((s t))
-  (report-bad-arg s '(and input-stream fundamental-binary-stream)))
+  (report-bad-arg s '(and input-stream binary-stream)))
 
 (defmethod stream-write-byte ((s t) b)
   (declare (ignore b))
-  (report-bad-arg s '(and output-stream fundamental-binary-stream)))
+  (report-bad-arg s '(and output-stream binary-stream)))
 
 (defmethod stream-length ((s stream) &optional new)
@@ -1584,4 +1626,7 @@
       (error "~s is closed" s)))
 
+(defmethod open-stream-p ((s string-stream))
+  (not (null (%string-stream-string s))))
+
 (defmethod close  ((s string-stream) &key abort)
   (declare (ignore abort))
@@ -1593,6 +1638,5 @@
 (defmethod print-object ((s string-stream) out)
   (print-unreadable-object (s out :type t :identity t)
-    (let* ((closed (slot-value s 'closed)))
-      (when closed (format out "~s" closed)))))
+    (unless (open-stream-p s)  (format out " ~s" :closed))))
 
 (defclass string-output-stream (string-stream fundamental-character-output-stream)
@@ -1806,4 +1850,8 @@
    (element-type :initarg :element-type :reader %buffered-stream-element-type)))
 
+(defmethod open-stream-p ((s buffered-stream-mixin))
+  (with-slots (ioblock) s
+    (not (null ioblock))))
+  
 (defun stream-ioblock (stream &optional (error-if-nil t))
   (with-slots (ioblock) stream