From 4608da2ac8d4bafa7b8acbd7a097e32e5eb2f764 Mon Sep 17 00:00:00 2001
From: Jose Antonio Ortega Ruiz <jao@gnu.org>
Date: Tue, 24 Feb 2009 02:18:28 +0100
Subject: Partial support for stack trace display.

---
 geiser/introspection.scm | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

(limited to 'geiser/introspection.scm')

diff --git a/geiser/introspection.scm b/geiser/introspection.scm
index 29d059b..ca6afae 100644
--- a/geiser/introspection.scm
+++ b/geiser/introspection.scm
@@ -64,13 +64,14 @@
         (else #f)))
 
 (define (symbol-module sym)
-  (call/cc
-   (lambda (k)
-     (apropos-fold (lambda (module name var init)
-                     (if (eq? name sym) (k (module-name module)) init))
-                   #f
-                   (symbol->string sym)
-                   (apropos-fold-accessible (current-module))))))
+  (and sym
+       (call/cc
+        (lambda (k)
+          (apropos-fold (lambda (module name var init)
+                          (if (eq? name sym) (k (module-name module)) init))
+                        #f
+                        (symbol->string sym)
+                        (apropos-fold-accessible (current-module)))))))
 
 (define (program-args program)
   (let* ((arity (program-arity program))
-- 
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