Document Type
Technical Report
Version
Author's Final Manuscript
Publication Date
2017
Abstract
Parametric polymorphism is one of the lynchpins of modern typed programming. A function that can work seamlessly over a variety of types simplifies code, helps to avoid errors introduced through duplication, and and is easy to maintain. However, polymorphism comes at a very real cost, one that each language with support for polymorphism has paid in different ways. This paper describes this cost, proposes a theoretically simple way to reason about the cost—that kinds, not types, are calling conventions—and details one approach to dealing with polymorphism that works in the context of a language, Haskell, that prizes both efficiency and a principled type system.
This approach, levity polymorphism, allows the user to abstract over calling conventions; we detail and verify restrictions that are necessary in order to compile levity-polymorphic functions. Lev- ity polymorphism has opened up surprising new opportunities for library design in Haskell.
DOI
http://doi.org/10.1145/3062341.3062357
Citation
R.A. Eisenberg and S. Peyton Jones 2017. "Levity Polymorphism." Proceeding PLDI 2017 Proceedings of the 38th ACM SIGPLAN Conference on Programming Language Design and Implementation: 525-539.
