Implementing first-class polymorphic delimited continuations by a type-directed selective CPS-transform

We describe the implementation of first-class polymorphic delimited continuations in the programming language Scala. We use Scala's pluggable typing architecture to implement a simple type and effect system, which discriminates expressions with control effects from those without and accurately tracks answer type modification incurred by control effects. To tackle the problem of implementing first-class continuations under the adverse conditions brought upon by the Java VM, we employ a selective CPS transform, which is driven entirely by effect-annotated types and leaves pure code in direct style. Benchmarks indicate that this high-level approach performs competitively. Categories and Subject Descriptors D.3.3 [Programming Languages]: Language Constructs and Features--Control structures General Terms Languages, Theory Keywords Delimited continuations, selective CPS transform, control effects, program transformation

• Type: Conference
• Year: 2009
• Where: ICFP
• Authors: Tiark Rompf, Ingo Maier, Martin Odersky
• Keywords: First-class Continuations, ICFP 2009, Keywords Delimited Continuations, Polymorphic Delimited Continuations, Programming Languages