A Higher-Order Implementation of Rewriting

Many automatic theorem-provers rely on rewriting. Using theorems as rewrite rules helps to simplify the subgoals that arise during a proof. LCF is an interactive theorem-prover intended for reasoning about computation. Its implementation of rewriting is presented in detail. LCF provides a family of rewriting functions, and operators to combine them. A succession of functions is described, from pattern matching primitives to the rewriting tool that performs most inferences in LCF proofs. The design is highly modular. Each function performs a basic, specific task, such as recognizing a certain form of tautology. Each operator implements one method of building a rewriting function from simpler ones. These pieces can be put together in numerous ways, yielding a variety of rewrit- ing strategies. The approach involves programming with higher-order functions. Rewriting functions are data values, produced by computation on other rewriting functions. The code is in daily use at Cambridge, demonstrating the practical use of functional programming.

No reviews yet.

No comments yet.