Formalising FinFuns – Generating Code for Functions as Data from Isabelle/HOL

  • Andreas Lochbihler
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5674)


FinFuns are total functions that are constant except for a finite set of points, i.e. a generalisation of finite maps. We formalise them in Isabelle/HOL and present how to safely set up Isabelle’s code generator such that operations like equality testing and quantification on FinFuns become executable. On the code output level, FinFuns are explicitly represented by constant functions and pointwise updates, similarly to associative lists. Inside the logic, they behave like ordinary functions with extensionality. Via the update/constant pattern, a recursion combinator and an induction rule for FinFuns allow for defining and reasoning about operators on FinFuns that directly become executable. We apply the approach to an executable formalisation of sets and use it for the semantics for a subset of concurrent Java.


Kernel Function Type Class Partial Function Recursive Call Recursive Equation 
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© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • Andreas Lochbihler
    • 1
  1. 1.Universität Karlsruhe (TH)Germany

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