Prolog list

Introduction to Prolog list

• The prolog list is a function for collecting several values to operate on large-size data.
• The list is a data structure for grouping the entity to handle the application’s data.
• The list is a collection to store multiple data items using brackets.
• The list is a data structure to create groups of the different values using square brackets.
• The prolog list is functional to store various data items, and it differs by using comma symbols.
• The prolog list is used to insert, delete, update, and append operations of the large values.
• The list is a function to handle and operate different entities in similar or different categories.

Syntax

• The prolog list uses square brackets [prolog list] to store data.
• The data list differs by a comma after a single value.
• The list syntax is shown below.
• [Value1, Value2, Value3, …, Value ]
• Description
  • The prolog list contains values of a similar category.
  • The square bracket contains values and differentiates these values using commas.

• The prolog empty list syntax is shown below.
• [ ]
• Description
  • The prolog list is either empty or non-empty.
  • If the list is empty, then the bracket does not contain any value.

• The prolog list works with the head.
• [Head | value1, value2, value3]
• The list works with a tail.
• [Head| tail1, tail2, tail3]
• Description
  • The vertical bar separates the head and tail of the list.
  • The first value is called the head of the list.
  • The other values except the first are called tail values.

• The list works with variables using the head.

[Head|_] = [Head| value1, value2, value].

• The list works with variables using a tail.

Tail = [value1, value2, value] Prolist = [value| Tail].

• Description
  • The prolog creates variables and contains lists with values.
  • If this variable list is required in the main list, then include it in the head or tail part.

• Some prolog list syntaxes are given below.

[v1, v2 | [v3] ] [v1, v2| [v3] ] [v1, v2, v3| [ ] ]

How does the list work in Prolog?

Prolog comment works in the “pl” file

• Create a file with the “pl” extension.

Example: main. pl

• Create a list with list multiple entities.

Plist([Australia, india, japan, UK, USA]).

Prolog comment works in the console

• Open console or interpreter.
• Set the directory path of the “pl” file.
• Use the given prolog file.

[main].

• Use the list in the console.

Plist([Australia, india, japan, UK, USA]).

• Directly use the list in the prolog console.

[1, 2, 3, 4, 5] = [Australia, India, Japan, UK, USA].

Prolog comment works in the console.

• Method1: use with multiple variables.

[1, 2, 3, 4, 5] = [Australia, India, Japan, UK, USA].

• The “1” number is assigned for Australia.

Australia = 1

• The “2” number is assigned for India.

India = 2

• The “3” number is assigned for Japan.

Japan = 3

• The “4” number is Assigned for the Uk.

UK = 4

• The “5” number is assigned for the USA.

USA = 5

• Method2: use with a single variable.

A = [Australia, India, Japan, UK, USA].

Examples

Here are the following examples mentioned below

Example1: the basic list with a single variable example and output are below.

• Prolog console

| ?- A = [Australia, India, Japan, UK, USA].

Output

• Prolog console

| ?- C = [1, 2, 3, 4, 5, 6, 7].

Output

• Prolog console

| ?- D = [India, 1, USA, uk].

Output

• Description:
  • The list contains a value in number, lowercase, and uppercase format.
  • The list assigns a single variable and displays the same as a program.

Example2: the basic prolog list with multiple variables examples and output is below.

• • Prolog console

[1, 2, 3, 4, 5] = [Australia, India, Japan, UK, USA].

Output

• Prolog console

[A, B, C, D, E] = [Australia, India, Japan, UK, USA].

Output

• Prolog console

[A, B, C, D, E] = [australia, india, japan, uk, usa].

Output

• Description:
  • The list contains a value in number, lowercase, and uppercase format.
  • The list assigns multiple variables and displays values with variables.

Example3: the list with tail example and the output shown below.

• • Prolog console

| ?- Tail = [australia, india, japan, england, america],
C = [ countries | Tail].

Output

• Description:
  • The prolog list specifies head and tail using a vertical bar.
  • The other values except the first value are called a tail of the list.

Example4: the list with a head example with a single variable.

• • Prolog console

| ?- [Head|_] = [australia, india, japan, england, america].

Output

• Description:
  • The list specifies head and tail using a vertical bar.
  • The first value is called the head of the list.

• Example5: the list with the required entity example and the output shows below.
  • Prolog console

| ?- [_,Value|_] = [australia, india, japan, england, america].

Output

• Prolog console

| ?- [_,_,Value|_] = [australia, india, japan, england, america].

Output

• Prolog console

| ?- [_,_,_,Value|_] = [australia, india, japan, england, america].

Output

• Description:
  • The list displays the required value using variable and underscores symbols.
  • You specify the position of the value using a comma and underscore symbol.

Example6: the basic list example and the output shows below.

• • pl file

cntry([australia, india, japan, england, america]).

• Prolog console

| ?- cntry(List).

Output

• Description:
  • The file contains a list with the required value.
  • You assign a list name with the required variable name.
  • The output displays a list with the variable name.

• Prolog console

| ?- [Head|Tail] = [Countries, australia, india, japan, england, america].

Output

• Description:
  • The list specifies head and tail using a vertical bar.
  • The first value is called the head of the list.
  • The other value is called the tail of the list.

Conclusion

• The list maintains a collection of the values in the applications.
• The prolog list operates on large size data of the database.
• The list creates applications that are user-friendly, fast, and lightweight.
•  The list operates efficiently.

Recommended Articles

This is a guide to the Prolog list. Here we discuss How does the list work in Prolog along with the description and outputs. You may also have a look at the following articles to learn more –

1. Linked List Types
2. Java Collection to List
3. Lua list
4. Skip List Java