Haskell Rules: Embedding Rule Systems in Haskell

We present a domain-specific embedded language that allows the definition of rule systems in Haskell. As one particular example, we consider the modeling of type systems, which is an important part of programming language design. Type systems are most conveniently described using rule systems. Our approach is well integrated into Haskell’s type system and thus facilitates the convenient modeling of type systems and language semantics in general. We also demonstrate how our DSEL allows functional-logic programming in Haskell. Our system generalizes previous work by operating on user-defined data types, taking advantage of static typing, representing rules as functions, and allows a creative integration of logical variables into data structures which generalizes two previous approaches. We describe a straightforward method for translating rule systems into our DSEL.