diff -r 0b8692959d37 -r 4779a6fb4fbe src/ucx/ucx/list.h
--- a/src/ucx/ucx/list.h	Tue Aug 25 12:07:56 2020 +0200
+++ b/src/ucx/ucx/list.h	Sat Oct 24 17:34:32 2020 +0200
@@ -57,7 +57,7 @@
  * @param elem The variable name of the element
  */
 #define UCX_FOREACH(elem,list) \
-        for (UcxList* elem = list ; elem != NULL ; elem = elem->next)
+        for (UcxList* elem = (UcxList*) list ; elem != NULL ; elem = elem->next)
 
 /**
  * UCX list type.
@@ -99,7 +99,7 @@
  * @param data additional data for the copy_func()
  * @return a pointer to the copy
  */
-UcxList *ucx_list_clone(UcxList *list, copy_func cpyfnc, void* data);
+UcxList *ucx_list_clone(const UcxList *list, copy_func cpyfnc, void* data);
 
 /**
  * Creates an element-wise copy of a list using a UcxAllocator.
@@ -117,7 +117,7 @@
  * @return a pointer to the copy
  * @see ucx_list_clone()
  */
-UcxList *ucx_list_clone_a(UcxAllocator *allocator, UcxList *list,
+UcxList *ucx_list_clone_a(UcxAllocator *allocator, const UcxList *list,
         copy_func cpyfnc, void* data);
 
 /**
@@ -328,7 +328,8 @@
  * @return the index of the element containing the specified data or -1 if the
  * data is not found in this list
  */
-ssize_t ucx_list_find(UcxList *list, void *elem, cmp_func cmpfnc, void *data);
+ssize_t ucx_list_find(const UcxList *list, void *elem,
+    cmp_func cmpfnc, void *data);
 
 /**
  * Checks, if a list contains a specific element.
@@ -342,7 +343,8 @@
  * @return 1, if and only if the list contains the specified element data
  * @see ucx_list_find()
  */
-int ucx_list_contains(UcxList *list, void *elem, cmp_func cmpfnc, void *data);
+int ucx_list_contains(const UcxList *list, void *elem,
+    cmp_func cmpfnc, void *data);
 
 /**
  * Sorts a UcxList with natural merge sort.
@@ -388,6 +390,120 @@
 UcxList *ucx_list_remove_a(UcxAllocator *allocator, UcxList *list,
         UcxList *element);
 
+/**
+ * Returns the union of two lists.
+ * 
+ * The union is a list of unique elements regarding cmpfnc obtained from
+ * both source lists.
+ * 
+ * @param left the left source list
+ * @param right the right source list
+ * @param cmpfnc a function to compare elements
+ * @param cmpdata additional data for the compare function
+ * @param cpfnc a function to copy the elements
+ * @param cpdata additional data for the copy function
+ * @return a new list containing the union
+ */
+UcxList* ucx_list_union(const UcxList *left, const UcxList *right,
+    cmp_func cmpfnc, void* cmpdata,
+    copy_func cpfnc, void* cpdata);
+
+/**
+ * Returns the union of two lists.
+ * 
+ * The union is a list of unique elements regarding cmpfnc obtained from
+ * both source lists.
+ * 
+ * @param allocator allocates the new list elements
+ * @param left the left source list
+ * @param right the right source list
+ * @param cmpfnc a function to compare elements
+ * @param cmpdata additional data for the compare function
+ * @param cpfnc a function to copy the elements
+ * @param cpdata additional data for the copy function
+ * @return a new list containing the union
+ */
+UcxList* ucx_list_union_a(UcxAllocator *allocator,
+    const UcxList *left, const UcxList *right,
+    cmp_func cmpfnc, void* cmpdata,
+    copy_func cpfnc, void* cpdata);
+
+/**
+ * Returns the intersection of two lists.
+ * 
+ * The intersection contains all elements of the left list
+ * (including duplicates) that can be found in the right list.
+ * 
+ * @param left the left source list
+ * @param right the right source list
+ * @param cmpfnc a function to compare elements
+ * @param cmpdata additional data for the compare function
+ * @param cpfnc a function to copy the elements
+ * @param cpdata additional data for the copy function
+ * @return a new list containing the intersection
+ */
+UcxList* ucx_list_intersection(const UcxList *left, const UcxList *right,
+    cmp_func cmpfnc, void* cmpdata,
+    copy_func cpfnc, void* cpdata);
+
+/**
+ * Returns the intersection of two lists.
+ * 
+ * The intersection contains all elements of the left list
+ * (including duplicates) that can be found in the right list.
+ * 
+ * @param allocator allocates the new list elements
+ * @param left the left source list
+ * @param right the right source list
+ * @param cmpfnc a function to compare elements
+ * @param cmpdata additional data for the compare function
+ * @param cpfnc a function to copy the elements
+ * @param cpdata additional data for the copy function
+ * @return a new list containing the intersection
+ */
+UcxList* ucx_list_intersection_a(UcxAllocator *allocator,
+    const UcxList *left, const UcxList *right,
+    cmp_func cmpfnc, void* cmpdata,
+    copy_func cpfnc, void* cpdata);
+
+/**
+ * Returns the difference of two lists.
+ * 
+ * The difference contains all elements of the left list
+ * (including duplicates) that are not equal to any element of the right list.
+ * 
+ * @param left the left source list
+ * @param right the right source list
+ * @param cmpfnc a function to compare elements
+ * @param cmpdata additional data for the compare function
+ * @param cpfnc a function to copy the elements
+ * @param cpdata additional data for the copy function
+ * @return a new list containing the difference
+ */
+UcxList* ucx_list_difference(const UcxList *left, const UcxList *right,
+    cmp_func cmpfnc, void* cmpdata,
+    copy_func cpfnc, void* cpdata);
+
+/**
+ * Returns the difference of two lists.
+ * 
+ * The difference contains all elements of the left list
+ * (including duplicates) that are not equal to any element of the right list.
+ * 
+ * @param allocator allocates the new list elements
+ * @param left the left source list
+ * @param right the right source list
+ * @param cmpfnc a function to compare elements
+ * @param cmpdata additional data for the compare function
+ * @param cpfnc a function to copy the elements
+ * @param cpdata additional data for the copy function
+ * @return a new list containing the difference
+ */
+UcxList* ucx_list_difference_a(UcxAllocator *allocator,
+    const UcxList *left, const UcxList *right,
+    cmp_func cmpfnc, void* cmpdata,
+    copy_func cpfnc, void* cpdata);
+
 #ifdef	__cplusplus
 }
 #endif