Make DMdA's fold more robust.

2011-01-15 13:07:33 +01:00 · 2011-01-15 13:07:33 +01:00 · 894c531f6c
commit 894c531f6c
parent 4ffb16905e
1 changed files with 9 additions and 1 deletions
--- a/collects/deinprogramm/DMdA.rkt
+++ b/collects/deinprogramm/DMdA.rkt
@ -429,7 +429,15 @@
      ((empty? lis) unit)
      ((pair? lis) 
       (combine (first lis)
-                (fold unit combine (rest lis)))))))
+                (fold unit combine (rest lis))))
+      (else
+       (raise
+	(make-exn:fail:contract
+	 (string->immutable-string
+	  (format "Argument zu fold keine Liste, sondern ~e; andere Argumente: ~e ~e"
+		  lis
+		  unit combine))
+	 (current-continuation-marks)))))))

 ;; This is copied from collects/lang/private/beginner-funs.ss
 ;; Test-suite support (require is really an effect