Exploring the Design Space of Higher-Order Casts

  • Authors:

  • Jeremy Siek;Ronald Garcia;Walid Taha

  • Affiliations:

  • University of Colorado, Boulder, USA CO 80309;Rice University, Houston, USA TX 77005;Rice University, Houston, USA TX 77005

  • Venue:
  • ESOP '09 Proceedings of the 18th European Symposium on Programming Languages and Systems: Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2009
  • Year:
  • 2009

Quantified Score

Hi-index 0.00

Visualization

Abstract

This paper explores the surprisingly rich design space for the simply typed lambda calculus with casts and a dynamic type. Such a calculus is the target intermediate language of the gradually typed lambda calculus but it is also interesting in its own right. In light of diverse requirements for casts, we develop a modular semantic framework, based on Henglein's Coercion Calculus, that instantiates a number of space-efficient, blame-tracking calculi, varying in what errors they detect and how they assign blame. Several of the resulting calculi extend work from the literature with either blame tracking or space efficiency, and in doing so reveal previously unknown connections. Furthermore, we introduce a new strategy for assigning blame under which casts that respect traditional subtyping are statically guaranteed to never fail. One particularly appealing outcome of this work is a novel cast calculus that is well-suited to gradual typing.