diff --git a/du6/list_ops.c b/du6/list_ops.c
index 6bf1e07..47df1a4 100644
--- a/du6/list_ops.c
+++ b/du6/list_ops.c
@@ -1,21 +1,16 @@
 #include <stdlib.h>
+#include <string.h>
 #include "list_ops.h"
 
-list_t *new_list(size_t length, list_element_t default_value) {
-    list_t *list = malloc(sizeof(list_t));
+list_t *new_list(size_t length, list_element_t elements[]) {
+    list_t *list = malloc(sizeof(list_t) + sizeof(list_element_t) * length);
     list->length = length;
-    list->elements = malloc(sizeof(list_element_t) * length);
-    for (size_t i = 0; i < length; ++i) {
-        list->elements[i] = default_value;
-    }
+    memcpy(list->elements, elements, sizeof(list_element_t) * length);
     return list;
 }
 
 void delete_list(list_t *list) {
-    if (list) {
-        free(list->elements);
-        free(list);
-    }
+    free(list);
 }
 
 size_t length_list(list_t *list) {
@@ -24,76 +19,72 @@ size_t length_list(list_t *list) {
 
 list_t *append_list(list_t *list1, list_t *list2) {
     size_t total_length = list1->length + list2->length;
-    list_t *new_list = malloc(sizeof(list_t));
-    new_list->length = total_length;
-    new_list->elements = malloc(sizeof(list_element_t) * total_length);
+    list_t *result = malloc(sizeof(list_t) + sizeof(list_element_t) * total_length);
+    result->length = total_length;
 
-    for (size_t i = 0; i < list1->length; ++i) {
-        new_list->elements[i] = list1->elements[i];
-    }
-    for (size_t i = 0; i < list2->length; ++i) {
-        new_list->elements[list1->length + i] = list2->elements[i];
-    }
+    memcpy(result->elements, list1->elements, sizeof(list_element_t) * list1->length);
+    memcpy(result->elements + list1->length, list2->elements, sizeof(list_element_t) * list2->length);
 
-    return new_list;
+    return result;
 }
 
 list_t *filter_list(list_t *list, bool (*filter_fn)(list_element_t)) {
     size_t count = 0;
-    for (size_t i = 0; i < list->length; ++i) {
+
+    for (size_t i = 0; i < list->length; i++) {
         if (filter_fn(list->elements[i])) {
             count++;
         }
     }
 
-    list_element_t *buffer = malloc(sizeof(list_element_t) * count);
+    list_element_t *filtered = malloc(sizeof(list_element_t) * count);
     size_t index = 0;
-    for (size_t i = 0; i < list->length; ++i) {
+    for (size_t i = 0; i < list->length; i++) {
         if (filter_fn(list->elements[i])) {
-            buffer[index++] = list->elements[i];
+            filtered[index++] = list->elements[i];
         }
     }
 
-    list_t *new_list = malloc(sizeof(list_t));
+    list_t *new_list = malloc(sizeof(list_t) + sizeof(list_element_t) * count);
     new_list->length = count;
-    new_list->elements = buffer;
+    memcpy(new_list->elements, filtered, sizeof(list_element_t) * count);
+    free(filtered);
+
     return new_list;
 }
 
 list_t *map_list(list_t *list, list_element_t (*map_fn)(list_element_t)) {
-    list_t *new_list = malloc(sizeof(list_t));
+    list_t *new_list = malloc(sizeof(list_t) + sizeof(list_element_t) * list->length);
     new_list->length = list->length;
-    new_list->elements = malloc(sizeof(list_element_t) * list->length);
 
-    for (size_t i = 0; i < list->length; ++i) {
+    for (size_t i = 0; i < list->length; i++) {
         new_list->elements[i] = map_fn(list->elements[i]);
     }
 
     return new_list;
 }
 
-list_element_t foldl_list(list_t *list, list_element_t init, list_element_t (*fn)(list_element_t, list_element_t)) {
-    list_element_t acc = init;
-    for (size_t i = 0; i < list->length; ++i) {
-        acc = fn(acc, list->elements[i]);
+list_element_t foldl_list(list_t *list, list_element_t initial, list_element_t (*fold_fn)(list_element_t, list_element_t)) {
+    list_element_t result = initial;
+    for (size_t i = 0; i < list->length; i++) {
+        result = fold_fn(result, list->elements[i]);
     }
-    return acc;
+    return result;
 }
 
-list_element_t foldr_list(list_t *list, list_element_t init, list_element_t (*fn)(list_element_t, list_element_t)) {
-    list_element_t acc = init;
-    for (size_t i = list->length; i > 0; --i) {
-        acc = fn(list->elements[i - 1], acc);
+list_element_t foldr_list(list_t *list, list_element_t initial, list_element_t (*fold_fn)(list_element_t, list_element_t)) {
+    list_element_t result = initial;
+    for (size_t i = list->length; i-- > 0;) {
+        result = fold_fn(list->elements[i], result);
     }
-    return acc;
+    return result;
 }
 
 list_t *reverse_list(list_t *list) {
-    list_t *new_list = malloc(sizeof(list_t));
+    list_t *new_list = malloc(sizeof(list_t) + sizeof(list_element_t) * list->length);
     new_list->length = list->length;
-    new_list->elements = malloc(sizeof(list_element_t) * list->length);
 
-    for (size_t i = 0; i < list->length; ++i) {
+    for (size_t i = 0; i < list->length; i++) {
         new_list->elements[i] = list->elements[list->length - i - 1];
     }