diff -r 85c08391a090 -r 7aaec630cf15 src/array_list.c
--- a/src/array_list.c	Thu Nov 17 18:32:59 2022 +0100
+++ b/src/array_list.c	Thu Nov 17 18:46:55 2022 +0100
@@ -232,7 +232,16 @@
         struct cx_list_s const *list,
         void const *elem
 ) {
-    return 0;
+    char *cur = ((cx_array_list const *) list)->data;
+
+    for (size_t i = 0; i < list->size; i++) {
+        if (0 == list->cmpfunc(elem, cur)) {
+            return i;
+        }
+        cur += list->itemsize;
+    }
+
+    return list->size;
 }
 
 static void cx_arl_sort(struct cx_list_s *list) {