Re: [Haskell] Re: refactoring, catamorphism, termination of programs
Dear Stefan, thanks for your comment. E.g. the Coq papers define its elimination constructs either as a catamorphism, or as a combination of casefix, where the recursive calls are appropriately restricted to pass subterms as arguments. if we replace the subterm ordering by some other well-founded ordering on terms, and let a tool look for this ordering, then we get the classical approach (that is used for term rewriting systems). my point is that most (Haskell) programs don't require this because they are (or should be) just primitive recursive functions (catamorphisms) over data structures, and in fact they should be presented as such (explicit recursion should be replaced by the catamorphism), and I want a tool to do that replacement. Sure, this will not solve all Haskell termination problems. I just want to see how many are left (e.g. from the functions in the Prelude, or in my programs). If you want to contribute further to the discussion, then please do so via http://groups.google.com/group/fp-termination (I don't want to clutter the haskell mailing list, but I want to have the discussion in some public place.) Best regards, -- -- Johannes Waldmann -- Tel/Fax (0341) 3076 6479/80 -- http://www.imn.htwk-leipzig.de/~waldmann/ --- ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
Re: [Haskell] Re: refactoring, catamorphism, termination of programs
On 2 May 2007, at 12:18, Johannes Waldmann wrote: If you want to contribute further to the discussion, then please do so via http://groups.google.com/group/fp-termination (I don't want to clutter the haskell mailing list, but I want to have the discussion in some public place.) Isn't Haskell Cafe exactly the place for that discussion? (As opposed to the Haskell mailing list.) Good luck with the discussion. Someone mentioned DrHylo; that's built on the work of Hu, Onoue and others from Tokyo on a system called Hylo: http://www.ipl.t.u-tokyo.ac.jp/~onoue/hylo/ See also Alberto Pardo's HFusion: http://www.fing.edu.uy/inco/proyectos/fusion/ Jeremy [EMAIL PROTECTED] Oxford University Computing Laboratory,TEL: +44 1865 283508 Wolfson Building, Parks Road, FAX: +44 1865 283531 Oxford OX1 3QD, UK. URL: http://www.comlab.ox.ac.uk/oucl/people/jeremy.gibbons.html ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
[Haskell] Re: refactoring, catamorphism, termination of programs
I'm looking for a tool that implements the source code transformation replace recursion by catamorphism (fold etc.). My application is that if the transformation succeeds, it implies that the program terminates. (roughly) I don't want to make a big research project out of this, rather I think of quickly putting together a prototype that proves the concept. Have you considered another approach? E.g. the Coq papers define its elimination constructs either as a catamorphism, or as a combination of casefix, where the recursive calls are appropriately restricted to pass subterms as arguments. See for example Eduardo Gimenez's Codifying guarded definition with recursive schemes. This paper also shows how to turn such a casefix into a call to a catamorphism. Stefan ___ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
