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Descriptor-Free Representation of Arrays with Dependent Types

  • Kai Trojahner
  • Clemens Grelck
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5836)

Abstract

Besides element type and values, a multidimensional array is characterized by the number of axes (rank) and their respective lengths (shape vector). Both properties are essential for bounds checking and to compute linear offsets into heap memory at run time. In order to have an array’s rank and shape available at any time during program execution, both are typically kept in an array descriptor that is maintained at run time in addition to the array itself.

In this paper, we propose a different approach: we treat array rank and shape as first-class citizens themselves. Firstly, we use dependent types to reflect structural properties of arrays in the type system. Secondly, we annotate a program with the explicit array properties wherever necessary. This choice not only renders implicit run time array descriptors obsolete, but exposing all rank and shape computations explicitly in intermediate code also allows us to perform extensive compile time optimisation on them. We have implemented the proposed approach in our experimental array language Qube; preliminary experimental results indicate the suitability of the proposed approach.

Keywords

Dependent Type Index Vector Type Check Shape Vector Array Property 
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 2011

Authors and Affiliations

  • Kai Trojahner
    • 1
  • Clemens Grelck
    • 2
    • 3
  1. 1.Institute of Software Technology and Programming LanguagesUniversity of LübeckGermany
  2. 2.Institute of InformaticsUniversity of AmsterdamNetherlands
  3. 3.School of Computer ScienceUniversity of HertfordshireUnited Kingdom

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