From abfc3de9ba237ece4d91daf7c9fe635efc478c19 Mon Sep 17 00:00:00 2001
From: Matthias Felleisen <matthias@ccs.neu.edu>
Date: Mon, 12 Mar 2012 22:49:10 -0400
Subject: [PATCH] error handler now uses Guillaume's rewrites

---
 collects/htdp/bsl/runtime.rkt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/collects/htdp/bsl/runtime.rkt b/collects/htdp/bsl/runtime.rkt
index 0a6ac65f79..7a87d47677 100644
--- a/collects/htdp/bsl/runtime.rkt
+++ b/collects/htdp/bsl/runtime.rkt
@@ -2,6 +2,7 @@
 (require mzlib/pconvert
          racket/pretty
          lang/private/set-result
+         lang/private/rewrite-error-message
          mrlib/image-core
          racket/snip
          racket/class)
@@ -63,6 +64,12 @@
        (define converted (print-convert v))
        (set-handlers
         (λ () (pretty-write converted))))))
+  (error-display-handler
+    (let ([o-d-h (error-display-handler)])
+      (lambda (msg exn)
+	(define x (get-rewriten-error-message exn))
+	(displayln `(hello ,x ,exn))
+	(o-d-h x exn))))
   (let ([orig (global-port-print-handler)])
     (global-port-print-handler
      (lambda (val port [depth 0])