Practical Variable-Arity Polymorphism

  • T. Stephen Strickland
  • Sam Tobin-Hochstadt
  • Matthias Felleisen
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5502)


Just as some functions have uniform behavior over distinct types, other functions have uniform behavior over distinct arities. These variable-arity functions are widely used in scripting languages such as Scheme and Python. Statically typed languages also accommodate modest forms of variable-arity functions, but even ML and Haskell, languages with highly expressive type systems, cannot type check the wide variety of variable-arity functions found in untyped functional languages. Consequently, their standard libraries contain numerous copies of the same function definition with slightly different names.

As part of the Typed Scheme project—an on-going effort to create an explicitly typed sister language for PLT Scheme—we have designed and implemented an expressive type system for variable-arity functions. Our practical validation in the context of our extensive code base confirms the usefulness of the enriched type system.


Type System Type Scheme Scheme Programmer Elimination Rule Standard Library 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • T. Stephen Strickland
    • 1
  • Sam Tobin-Hochstadt
    • 1
  • Matthias Felleisen
    • 1
  1. 1.PLT @ Northeastern UniversityUSA

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