Prolog - Lists - Tutorialspoint

Home Whiteboard Graphing Calculator Online Compilers Articles Tools Chapters Categories Library Courses Certifications Login

• 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

• Selected Reading
• UPSC IAS Exams Notes
• Developer's Best Practices
• Questions and Answers
• Effective Resume Writing
• AI Based Resume Builder
• Personal AI Study Assistant
• Generate Coding Logic
• HR Interview Questions
• Computer Glossary
• Who is Who

Home Prolog Prolog Lists Prolog - Lists Previous Quiz Next

In this chapter, we will discuss one of the important concepts in Prolog, The Lists. It is a data structure that can be used in different cases for non-numeric programming. Lists are used to store the atoms as a collection.

In the subsequent sections, we will discuss the following topics −

• Representation of lists in Prolog

• Basic operations on prolog such as Insert, delete, update, append.

• Repositioning operators such as permutation, combination, etc.

• Set operations like set union, set intersection, etc.

Representation of Lists

The list is a simple data structure that is widely used in non-numeric programming. List consists of any number of items, for example, red, green, blue, white, dark. It will be represented as, [red, green, blue, white, dark]. The list of elements will be enclosed with square brackets.

A list can be either empty or non-empty. In the first case, the list is simply written as a Prolog atom, []. In the second case, the list consists of two things as given below −

• The first item, called the head of the list;

• The remaining part of the list, called the tail.

Suppose we have a list like: [red, green, blue, white, dark]. Here the head is red and tail is [green, blue, white, dark]. So the tail is another list.

Now, let us consider we have a list, L = [a, b, c]. If we write Tail = [b, c] then we can also write the list L as L = [ a | Tail]. Here the vertical bar (|) separates the head and tail parts.

So the following list representations are also valid −

• [a, b, c] = [a | [b, c] ]

• [a, b, c] = [a, b | [c] ]

• [a, b, c] = [a, b, c | [ ] ]

For these properties we can define the list as −

A data structure that is either empty or consists of two parts − a head and a tail. The tail itself has to be a list.

Creating a List of three atoms.

Program (list_basics.pl)

:- initialization(main). main :- write([a, b, c]).

Output

| ?- consult('D:/TP Prolog/Sample Codes/list_basics.pl'). compiling D:/TP Prolog/Sample Codes/list_basics.pl for byte code... D:/TP Prolog/Sample Codes/list_basics.pl compiled, 1 lines read - 419 bytes written, 3 ms [a,b,c] yes | ?-

Creating a List of two atoms and a tail of one atom.

Program (list_basics.pl)

:- initialization(main). main :- write([a, b | [c] ]).

Output

| ?- consult('D:/TP Prolog/Sample Codes/list_basics.pl'). compiling D:/TP Prolog/Sample Codes/list_basics.pl for byte code... D:/TP Prolog/Sample Codes/list_basics.pl compiled, 1 lines read - 419 bytes written, 3 ms [a,b,c] yes | ?-

Creating a List of three atoms and an empty tail

Program (list_basics.pl)

:- initialization(main). main :- write([a, b, c | [ ] ]).

Output

| ?- consult('D:/TP Prolog/Sample Codes/list_basics.pl'). compiling D:/TP Prolog/Sample Codes/list_basics.pl for byte code... D:/TP Prolog/Sample Codes/list_basics.pl compiled, 1 lines read - 419 bytes written, 3 ms [a,b,c] yes | ?- Print Page Previous Next Advertisements