The article proposes a formalism that supports the relative definition of programming languages, allowing you to clearly express the difference between languages when analyzing and comparing them, as well as when defining new languages based on already known ones. Formalism is an extension of the BNF, in which the names of the concepts used can be accompanied by an indication of foreign concepts from other languages. As a result, it becomes possible to specify parts of the used concept, such as variants of the definition or implicit concepts, up to a syntactic position. The syntactic position can be specified using a terminal string, symbolizing the choice of a variant of the definition of a concept or indicating an implicit concept, the unnamed definition of which is located immediately after the string.

programming language definition, comparison of programming languages, BNF extension, general concepts, foreign concepts, implicit concepts, syntactic position, functional programming

Gorodnyaya Lidia Vasiljevna,  ,  orcid.org/0000-0002-4639-9032,  A.P. Ershov Institute of Informatics Systems; Novosibirsk State University