Declarative programming languages

These include functional and logical programming languages. Functional programming is a way of composing programs in which the only action is a function call. Functional programming does not use memory, as a place to store data, and, therefore, does not use intermediate variables, assignment operators, and cycles. The key concept in functional languages ​​is expression. A program written in a functional language is a sequence of descriptions of functions and expressions. The expression is calculated by reducing the complex to the simple. All expressions are written as lists. The first language was Lisp ( LISP , LIST Processing-list processing) created in 1959. This language allows you to handle large amounts of textual information. Logical programming is programming in terms of logic. In 1973, the artificial intelligence language Prologue ( PROLOG ) (Programming in Logic) was created. A program in the Prolog language is built from a sequence of facts and rules, then a statement is formulated that Prolog tries to prove with the help of the rules. The language itself is looking for a solution using the search and matching methods that it contains. Logic programs are not distinguished by high speed, since the process of their execution is reduced to the construction of direct and reverse chains of reasoning by various search methods.

Functional programming

A program consists of a set of functions that call each other. Variables may not be present at all. Algorithms written in a functional form are usually shorter and contain fewer errors than similar object-oriented or procedural ones. Functional programming is considered to be an ultra-high level programming. The languages ​​of this group have relatively low speed due to the complexity of implementation.

Logic programming

It is based on formal logic and Boolean algebra (in some languages, fuzzy logic tools are used, which allows the creation of artificial intelligence systems). A program written in a logical programming language does not contain specific algorithms (actions and commands like do this, then this). A description of the conditions of the problem and logical relations is given, according to which the programming system itself calculates the possible consequences and relationships of the entered data and formulas.