handle empty structs

svn: r9055
2008-03-22 01:37:55 +00:00 · 2008-03-22 01:37:55 +00:00 · 3552f7f73b
commit 3552f7f73b
parent b7127dc9c7
1 changed files with 1 additions and 1 deletions
--- a/collects/scheme/match/parse.ss
+++ b/collects/scheme/match/parse.ss
@ -193,7 +193,7 @@
         (let* (;; the accessors come in reverse order
                [acc (reverse acc)]
                ;; remove the first element, if it's #f
-                [acc (if (not (car acc)) (cdr acc) acc)])
+                [acc (cond [(null? acc) acc] [(not (car acc)) (cdr acc)] [else acc])])
           (make-Struct id pred (get-lineage #'s) acc 
                        (if (eq? '_ (syntax-e #'pats))
                            (map make-Dummy acc)