Interpreter prototypes from formal language definitions

Denotational semantics is now used widely for the formal definition of programming languages but there is a lack of appropriate tools to support language development. General purpose language implementation systems are oriented to syntax with poor support for semantics. Specialised denotational semantics based systems correspond closely to the formalism but are rendered inflexible for language experimentation by their monolithic multiple stages Exploratory language development with formal definitions is better served by a unitary notation, encompassing syntax and semantics, which is close to but simpler than denotational semantics. Interactive implementation of the notation then facilitates language investigation through the direct execution of a formal definition as an interpreter for the defined language. This thesis presents Navel, a run-time typed, applicative order, pure functional programming language with integrated context free grammar rules. Navel has been used to develop prototype implementations from substantial formal language definitions, including for Navel itself. The Navel implementation achieves a performance which enables interactive language experimentation and compares well with that of contemporaneous declarative language implementations. Denotational semantics does not address concrete syntax issues and denotational semantics based systems either ignore or have ad-hoc provision for context sensitivity. In Navel, rules are full values. Abstraction over rules enables the concise expression of context sensitivity in a style similar to dynamic syntax.