Data Types in Prolog
Prolog is a logic programming language that supports several data types. Here are some of the main data types in Prolog with examples:
- Atom: An atom is a constant with a name that starts with a lowercase letter or a single quote. Atoms are often used to represent names, labels, and constants.
Examples:
john
'my atom'
hello_world
- Number: A number is a constant that represents a numerical value. Prolog supports integers, floating-point numbers, and scientific notation.
Examples:
42
-3
3.14
1.23e10
- Variable: A variable is a placeholder that can stand for any term. Variables start with an uppercase letter or an underscore.
Examples:
X
_Y
- List: A list is a collection of terms enclosed in square brackets, separated by commas. Lists can contain any Prolog terms, including other lists.
Examples:
[1, 2, 3]
[apple, orange, banana]
[1, [2, 3], 4]
[] % an empty list
- Structure: A structure is a compound term that consists of a functor (an atom) and one or more arguments. The number of arguments is called the arity of the structure.
Examples:
point(3, 4)
person(john, 25, male)
6. Boolean: Prolog does not have a built-in Boolean data type, but Boolean values can be represented as atoms or variables. Conventionally, the atom true
represents true and the atom false
represents false.
example
true
false
X = true % variable X can be true or false
These are some of the main data types in Prolog. It's worth noting that Prolog is a dynamically typed language, so variables can change their type during execution.