The main results in both theoretical and practical application, accumulated so far in the field of functional and logical programming, are considered. It has been shown that both of these approaches related to the declarative programming paradigm make it possible to obtain new opportunities in terms of transformation and automatic synthesis of programs, proof of program properties, partial calculations, etc. Areas where application of these approaches has advantages over operator programming are described. Practical aspects of functional programming are studied using the example of Haskell languages ​ ​ - the best modern implementation of the functional paradigm. The theoretical justification provides the most important (for these purposes) results of lambda calculus and combinatorial logic.