FPH: First-class polymorphism for Haskell

  • Dimitrios Vytiniotis ,
  • Simon Peyton Jones ,
  • Stephanie Weirich

Proceedings of the 13th ACM SIGPLAN International Conference on Functional Programming |

Published by Association for Computing Machinery, Inc.

Publication | Publication

Languages supporting polymorphism typically have ad-hoc restrictions on where polymorphic types may occur. Supporting “firstclass” polymorphism, by lifting those restrictions, is obviously desirable, but it is hard to achieve this without sacrificing type inference. We present a new type system for higher-rank and impredicative polymorphism that improves on earlier proposals: it is an extension of Damas-Milner; it relies only on System F types; it has a simple, declarative specification; it is robust to program transformations; and it enjoys a complete and decidable type inference algorithm.