Continuations and Martin-Löf's type theory : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Computer Science at Massey University, Albany, New Zealand

Abstract

M-LTT is a theory designed to formalize constructive mathematics. By appealing to the Curry-Howard 'propositions as types' analogy, and to the Brouwer-Heyting-Kolmogorov interpretation of intuitionistic logic we can treat M-LTT as a framework for the specification and derivation of correct functional programs. However, programming in M-LTT has two weaknesses: we are limited in the functions that we can naturally express; the functions that we do write naturally are often inefficient. Programming with continuations allows us partially to address these problems. The continuation-passing programming style is known to offer a number of advantages to the functional programmer. We can also observe a relationship between continuation passing and type lifting in categorial grammar. We present computation rules which allow us to use continuations with inductively-defined types, and with types not presented inductively. We justify the new elimination rules using the usual proof-theoretic semantics. We show that the new rules preserve the consistency of the theory. We show how to use well-orderings to encode continuation-passing operators for inductively defined types.