Cutting Out Continuations

Abstract

Abstract. In the field of program transformation, one often transforms programs into continuation-passing style to make their flow of control explicit, and then immediately removes the resulting continuations using defunctionalisation to make the programs first-order. In this article, we show how these two transformations can be fused together into a single transformation step that cuts out the need to first introduce and then eliminate continuations. Our approach is calculational, uses standard equational reasoning techniques, and is widely applicable.

Programming language semantics: It’s easy as 1,2,3

“…This section is based upon (Hutton & Wright, 2006;Hutton & Bahr, 2016), which also show how to calculate machines for extended versions of the expression language and how the two transformation steps can be fused into a single step. Similar techniques can be used to calculate compilers for stack (Bahr & Hutton, 2015) and register machines (Hutton & Bahr, 2017;Bahr & Hutton, 2020), as well as typed (Pickard & Hutton, 2021), non-terminating (Bahr & Hutton, 2022) and concurrent (Bahr & Hutton, 2023) languages.…”