1 / 10

Dynamic-frame specifications in Dafny

Dynamic-frame specifications in Dafny. K. Rustan M. Leino RiSE , Microsoft Research. 17 July 2009 JML seminar Dagstuhl , Germany. Dafny. experimental language sequential, object based (no subclassing ) specifications in the style of dynamic frames

woods
Download Presentation

Dynamic-frame specifications in Dafny

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Dynamic-frame specifications in Dafny K. Rustan M. Leino RiSE, Microsoft Research 17 July 2009JML seminarDagstuhl, Germany

  2. Dafny • experimental language • sequential, object based (no subclassing) • specifications in the style of dynamic frames • coarse-grained frames (at the level of whole objects, not individual memory locations)

  3. Functional-correctness verifications • queue • linked list with head/tail pointers • in-situ list reversal • integer set • binary tree • Schorr-Waite marking algorithm

  4. Dafny grammar • Program ::= Class* • Class ::= class C<TypeParam*> { Member* } • Member ::= • Field • Method • Function

  5. Dynamic frames • A frame is a set of locations • A dynamic frame (in the sense of Dafny) is an expression that denotes a frame • Methods have modifies clauses • Functions have reads clauses

  6. Demo

  7. Lessons, 0 • Dynamic-frame specifications are useful and flexible • A language design around dynamic frames can be simple • Thus good in teaching? • Specifications are verbose, but perhaps simplification techniques can be applied (like in Spec# or Chalice) • Currently missing in Dafny: scopes for axioms

  8. Lessons, 1 • Pure methods are hard, functions are easy • SMT solvers work better with ghost fields than with functions • Reachability is not always necessary in specifications • Sets and sequences are nice as value types • Generics are a cinch • Decreases bound checks can be more liberal than naïve translation

  9. Lessons, 2 • SMT solvers can be used for functional-correctness verification • Inductive predicates seem useful • cases fit nicely with matching triggers • take us in the direction of the input languages of interactive theorem provers • Need: better views/visualizations of program states to clarify error messages and, generally, what’s going on

  10. Try it for yourself • Dafny is available as open source:http://boogie.codeplex.com

More Related