The issues of the functional programming style are considered from the standpoint of a declarative approach, which allows to increase the intelligence of developed programs in comparison with traditional programming. The functional language Lisp is considered as the basic language. The presentation is accompanied by numerous examples of specific programs. The textbook is intended for students of all forms of education and additional education in the specialty 220400 "Computer software and automated systems," specialty 351500 "Mathematical support and administration of information systems."