A calculus for modular and extensible language definition in LDL

A new approach to modularity and extensibility in specification of languages is presented. The considerations are based on the specification formalisms and the model of language definition of LDL. Namely, LDL language definitions consist of . GSFs - a special kind of attribute grammars - usually exploited for specification of syntax and semantic structure and . recursive function definitions (RFDs) for interpreting names of semantic functions applied in a GSF as well as for separate (dynamic) semantics descriptions (primary in the denotational style). In this presentation we concentrate on the extensibility of GSF schemes (parameterized context-free grammars with relational formulae on the parameters). In our approach, extensibility is obtained by first establishing a calculus providing operations over GSF schemes and second propagating a particular style of extensible definition of GSF schemes by instrumenting terms like . (attribution) transformers defined in terms of op..