Aspect-Oriented Compilers

Aspect-oriented programming provides the programmer with means to cross-cut conventional program structures, in particular the class hierarchies of object-oriented programming. This paper studies the use of aspect orientation in structuring syntax directed compilers. Syntax-directed compilers are often speci ed by means of attribute grammars. Such speci cations are typically structured by production | it is hard to structure them by semantic aspects such as `environment', `lexical level' and `type checking'. Even if such structuring is allowed at a syntactic level, it is certainly not possible to parameterise compiler aspects, and to treat them as rst-class objects in the speci cation language. In this paper we propose a technique for making compiler `aspects' rst-class objects, that can be stored, manipulated and combined. We propose a modest set of combinators that achieve this task in the functional programming language Haskell. The combinator library is an application of recent work on polymorphic type systems for record operations, in particular that of Gaster and Jones, and also of a technique due to R emy, which types symmetric record concatenation `for free'. It is hoped that this embedding of an aspect-oriented programming style in Haskell provides a stepping stone towards a more general study of the semantics of aspect-oriented programming.