Proof

Abstract

In this chapter we examine ways in which functional programs can be proved correct. For a number of reasons this is easier for functional, than for imperative, programs. In the simplest cases functional programs are equations, so the language documents itself, as it were. Beyond this we often have a higher-level expression of properties, by means of equations between functions rather than values. We can also express properties which cannot simply be discussed for imperative programs, using notations for lists and other algebraic data types, for instance.