Prolog - List Manipulation Predicates

Prolog provides various predicates to manipulate list. Following is the list of useful predicates to manipulate elements of the List −

Example - append(List1, List2, Result)

append predicates append List1 to List2 and set the updated list to Result. It can be used to get prefix or suffix of the lists.

Output

| ?- append([a, b], [c, d], X).

X = [a,b,c,d]

yes
| ?- append(X, [c, d], [a, b, c, d]). % find the prefix

X = [a,b]

yes
| ?- append([a, b], X, [a, b, c, d]). % find the suffix

X = [c,d]

yes
| ?- 

Example - reverse(List, ReversedList)

reverse predicate reverses the List and stores in ReversedList.

Output

| ?- reverse([a, b, c], R).   % reverse the list

R = [c,b,a]

yes
| ?- 

Example - sort(List, SortedList)

sort predicate sorts the List using standard order while removing the duplicates and stores in SortedList.

Output

| ?- sort([3, 1, 4, 1, 5, 9, 2], S). % sort the list

S = [1,2,3,4,5,9]

yes
| ?- 

Example - msort(List, SortedList)

msort predicate sorts the List using merge sort while preserving the duplicates and stores in SortedList.

Output

| ?- msort([3, 1, 4, 1, 5, 9, 2], S). % sort the list

S = [1,1,2,3,4,5,9]

yes
| ?-