fix part of #53, assertion failure in print_traverse

print.c

@@ -89,6 +89,9 @@ void print_traverse(value_t v)
         for(i=0; i < vector_size(v); i++)
             print_traverse(vector_elt(v,i));
     }
+    else if (iscprim(v)) {
+        // don't consider shared references to e.g. chars
+    }
     else if (isclosure(v)) {
         mark_cons(v);
         function_t *f = (function_t*)ptr(v);

tests/unittest.lsp

@@ -292,5 +292,14 @@
 
 (assert (equal? 1.0 (* 1.0 1))) ; tests that * no longer does inexact->exact
 
+(define (with-output-to-string nada thunk)
+  (let ((b (buffer)))
+    (with-output-to b (thunk))
+    (io.tostring! b)))
+
+(let ((c #\a))
+  (assert (equal? (with-output-to-string #f (lambda () (print (list c c))))
+                  "(#\\a #\\a)")))
+
 (princ "all tests pass\n")
 #t