1.2.1 Metalanguage
A metalanguage describes another language or some aspect of another language. Some metalanguages for compiler parts are well known. Regular expressions can describe tokens, and Backus-Naur form (BNF) can describe the syntax of a programming language. When we add attributes and semantic functions to BNF, creating an attribute grammar , we can describe the semantics of a programming language, as well as the syntax.
Some metalanguages can be used to describe themselves. The term unstratified refers to the self-description property of a metalanguage. A good metalanguage is unstratified.
Properties of Good metalanguages
