Added nested multi-line comments. The implementation has two

drawbacks:
1.) Since # and | may be part of an identifier, a#|bla|# is
read as a#|bla|# not as a.

2.) The REPL won't read a comment for its own, it will wait for
another value:
>#|bla|#

3
3
>

scheme/rts/read.scm

@@ -41,6 +41,30 @@
 ;         was sub-read ^
 
 
+(define (multi-line-comment-skip c port)
+  (read-char port)
+  (let lp ((state 0) (nested? #f))
+    (let* ((advance-one-of-two 
+	    (lambda (look-for1 state1 look-for2 state2 nested?)
+			  (let ((c (read-char port)))
+			    (if (eof-object? c)
+				(error 
+			 "EOF inside block comment -- #| missing a closing |#")
+				(lp (cond ((char=? c look-for1) state1)
+					  ((char=? c look-for2) state2)
+					  (else 0)) nested?)))))
+	   (advance-if (lambda (look-for state nested?)
+			 (advance-one-of-two look-for state 
+					     look-for state 
+					     nested?))))
+      (case state
+	((0) (advance-one-of-two #\| 1 #\# 5 nested?))
+	((1) (advance-if #\# 2 nested?))
+	((2) (if nested? #f (sub-read port)))
+	((5) (advance-if #\| 6 nested?))
+	((6) (lp 0 #t) (lp 0 nested?))))))
+    
+
 ; scsh stop
 
 (define (read . port-option)
@@ -259,6 +283,8 @@
 
 (define-sharp-macro #\! script-skip)
 
+(define-sharp-macro #\| multi-line-comment-skip)
+
 ; Tokens
 
 (define (sub-read-token c port)