- Prolog - Home
- Prolog - Introduction
- Prolog - Environment Setup
- Prolog - Hello World
- Prolog - Basics
- Prolog - Relations
- Prolog - Data Objects
- Loop & Decision Making
- Conjunctions & Disjunctions
Prolog Operators
- Prolog - Type of Operators
- Prolog - Arithmetic Comparison Operators
- Prolog - Unification Operators
- Prolog - Term Comparision Operators
- Prolog - Arithmetic Operators
- Prolog - Logical Operators
- Prolog - List Operators
- Prolog - Custom Operators
Prolog Lists
- Prolog - Lists
- Prolog - Member of List
- Prolog - Length of List
- Prolog - Concatenating Lists
- Prolog - Appending to a List
- Prolog - Deleting from a List
- Prolog - Inserting into a List
- Prolog - Permutation Operation
- Prolog - Combination Operation
- Prolog - Reverse Items of a List
- Prolog - Shift Items of a List
- Prolog - Check Order of a List
- Prolog - SubSet of a Set
- Prolog - Union of Sets
- Prolog - Intersection of Sets
- Prolog - Even and Odd Length Finding
- Prolog - Divide a List
- Prolog - Find Maximum of a List
- Prolog - Find Minimum of a List
- Prolog - Find Sum of a List
- Prolog - Sorting List using MergeSort
Built-In Predicates
- Prolog - Built-In Predicates
- Prolog - Identifying Terms
- Prolog - Decomposing Structures
- Prolog - Collecting All
- Prolog - Mathematical Predicates
- Prolog - Scientific Predicates
Miscellaneous
- Recursion and Structures
- Prolog - Backtracking
- Prolog - Preventing Backtracking
- Prolog - Different and Not
- Prolog - Inputs and Outputs
- Tree Data Structure (Case Study)
- Prolog - Examples
- Prolog - Basic Programs
- Prolog - Practical Arithmetic Examples
- Prolog - Examples of Cuts
- Towers of Hanoi Problem
- Prolog - Linked Lists
- Monkey and Banana Problem
- Prolog Useful Resources
- Prolog - Quick Guide
- Prolog - Useful Resources
- Prolog - Discussion
Prolog - List Operators
Prolog handles List in a very natural way. It is very easy to create and manipulate List in Prolog. Although there are no standard operators to work with List but Prolog provides various predicates to perform actions on the list. Following is the list of useful operators and predicates −
| Operator | Meaning |
|---|---|
| | | List Constructor, | (Vertical Bar) |
| [] | Empty List |
| [element1, element2,...] | To create list of element1, element2,... |
Common List Predicates
| Predicate | Usage |
|---|---|
| member(Element, List) | Succeeds if Element is part of the List. |
| append(List1, List2, Result) | appends List2 to List and returns Result as resulted List. |
| length(List, Length) | Unifies Length as the size of the List. |
| select(Element, List, RemainingList) | Succeeds if Element is removed from the List and remaining elements are returned as RemainingList. |
| nth0(Index, List, Element) | Accesses the Element from the List using zero based index. |
| nth1(Index, List, Element) | Accesses the Element from the List using one based index. |
| reverse(List, ReversedList) | Reverves the List and returns ReversedList. |
| sort(List, SortedList) | Sorts the List and returns SortedList. |
| msort(List, SortedList) | Sorts the List using merge sort while preseving the duplicates and returns SortedList. |
List Constructor, | (Vertical Bar)
Vertical Bar is the main operator to construct a List in Prolog.
Syntax
[Head | Tail]
Where −
Head − represents the first element of the list. We can have multiple elements in Head section as well.
Tail − represents the remaining elements of the list.
Example
| ?- [H | T] = [1, 2, 3, 4, 5]. H = 1 T = [2,3,4,5] yes | ?- [First, Second | Rest] = [a, b, c, d, e]. First = a Rest = [c,d,e] Second = b (16 ms) yes | ?-
Empty List, []
Empty List is a special atom to represent list of no items. It acts as a base case for all Lists.
Syntax
[]
List using literals, [element1, element2,...]
List using literals is a syntactic sugar replacing repeated use of | and [].
For example, if we want to create a list of 1,2,3.
[1 | (2 | (3 | []))]
We can create above list as shown below −
[1, 2, 3]List Predicates For Access with Examples List Predicates For Manipulation with Examples