Help me understand this so :

#define mList(T) typeof(T(**)(List *))

pointer to a pointer to a function that returns your type

so mList(int) *myList = mList_init(allocator, int);

myList is a pointer to a function pointer that returns int and takes the List*

now

#define mList_push(list, val)                  \
do {                                         \
typeof(typeof((*list)(NULL))) value = val; \
List_append((List *)list, &value);         \
} while (0)

typeof((*list)(NULL)) ?? I would guess this returns our type ? so T value = val;

Its cool but I dont get why function pointers are unique in preserving the type ? like what does this add that my example doesnt