Gesellschaft fr Informatik e.V.

Lecture Notes in Informatics


INFORMATIK 2009 - Im Focus das Leben P-154, 2916-2930 (2008).

Gesellschaft für Informatik, Bonn
2008


Editors

Stefan Fischer, Erik Maehle, Rüdiger Reischuk (eds.)


Copyright © Gesellschaft für Informatik, Bonn

Contents

Taming Selective Strictness

Daniel Seidel and Janis Voigtländer

Abstract


Free theorems establish interesting properties of parametrically polymorphic functions, solely from their types, and serve as a nice proof tool. For pure and lazy functional programming languages, they can be used with very few preconditions. Unfortunately, in the presence of selective strictness, as provided in languages like Haskell, their original strength is reduced. In this paper we present an approach for restrengthening them. By a refined type system which tracks the use of strict evaluation, we rule out unnecessary restrictions that otherwise emerge from the general suspicion that strict evaluation may be used at any point. Additionally, we provide an implemented algorithm determining all refined types for a given term.


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Gesellschaft für Informatik, Bonn
ISBN 978-3-88579-241-3


Last changed 24.01.2012 22:11:12