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commit 3b5732fb6ea24216ec83cd8bba3add7788bc141a
parent ea26c3f5ef14cf1eb188cc4344042ff9de9fbaef
Author: Ryan Culpepper <ryanc@racket-lang.org>
Date:   Fri,  9 Feb 2007 18:21:10 +0000

Macro stepper: fixed internal error

svn: r5583

original commit: 94ee28f1d50be46f7e0e759c3758af3781bcc54a

Diffstat:
M
collects/macro-debugger/model/reductions.ss
 | 
3
++-

1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/collects/macro-debugger/model/reductions.ss b/collects/macro-debugger/model/reductions.ss
@@ -245,7 +245,8 @@
                   (let ([ctx (lambda (x) (path-replace term path0 x))])
                     (append (with-context ctx
                               (reductions deriv0))
-                            (loop (path-replace term path0 (deriv-e2 deriv0))
+                            (loop (and (deriv? deriv0)
+                                       (path-replace term path0 (deriv-e2 deriv0)))
                                   (cdr subterms)))))]
                [(s:rename? (car subterms))
                 (let* ([subterm0 (car subterms)])