check for chars

src/rustint/core.clj

@@ -2531,6 +2531,7 @@
 
 (defn especificador-formato [arg, rustf]
   (cond
+    (char? arg) "%c"
     (string? arg) "%s"
     (int? arg) "%d"
     (and (float? arg) (nil? rustf) (== (pasar-a-int arg) arg)) "%.0f"