2. Functional Programming in HOL

Abstract

This chapter describes how to write functional programs in HOL and how to verify them. However, most of the constructs and proof procedures introduced are general and recur in any specification or verification task. We really should speak of functional modelling rather than functional programming: ou r primary aim is not to write programs but to design abstract models of systems. HOL is a specification language that goes well beyond what can be expressed as a program. However, for the time being we concentrate on the computable.

If you are a purist functional programmer, please note that all functions in HOL must be total:they must terminate for all inputs. Lazy data structures are not directly available.