A Dynamic Continuation-Passing Style for Dynamic Delimited Continuations

Abstract

We put a pre-existing definitional abstract machine for dynamic delimited continuations in defunctionalized form, and we present the consequences of this adjustment.<br /> <br />We first prove the correctness of the adjusted abstract machine. Because it is in defunctionalized form, we can refunctionalize it into a higher-order evaluation function. This evaluation function, which is compositional, is in continuation+state passing style and threads a trail of delimited continuations and a meta-continuation. Since this style accounts for dynamic delimited continuations, we refer to it as `dynamic continuation-passing style' and we present the corresponding dynamic CPS transformation. We show that the notion of computation induced by dynamic CPS takes the form of a continuation monad with a recursive answer type and we present a new simulation of dynamic delimited continuations in terms of static ones as well as new applications of dynamic delimited continuations.<br /> <br />The significance of the present work is that the computational artifacts surrounding dynamic CPS are not independent designs: they are mechanical consequences of having put the definitional abstract machine in defunctionalized form.