Representing Proof Transformations for Program Optimization

. In the proofs as programs methodology a program is derived from a formal constructive proof. Because of the close relationship between proof and program structure, transformations can be applied to proofs rather than to programs in order to improve performance. We describe a method for implementing transformations of formal proofs and show that it is applicable to the optimization of extracted programs. The method is based on the representation of derived logical rules in Elf, a logic programming language that gives an operational interpretation to the Edinburgh Logical Framework. It results in declarative implementations with a general correctness property that is verified automatically by the Elf type checking algorithm. We illustrate the technique by applying it to the problem of transforming a recursive function definition to obtain a tail-recursive form. 1 Introduction Research in constructive logics and type theories has resulted in a good understanding of the relation of form..