Hi Alberto, Take a look at ESC/Haskell and Sound Haskell, which provide mechanisms for doing some of the things you want. I don't think they integrate with type classes in the way you mention, but I think that is just a question of syntax. http://www.cl.cam.ac.uk/~nx200/ Thanks Neil This material is sales and trading commentary and does not constitute investment research. Please follow the attached hyperlink to an important disclaimer <www.credit-suisse.com/emea/legal <outbind://4/www.credit-suisse.com/emea/legal> > ________________________________ From: haskell-cafe-bounces@haskell.org [mailto:haskell-cafe-bounces@haskell.org] On Behalf Of Alberto G. Corona Sent: 22 October 2008 1:43 pm To: haskell-cafe@haskell.org Subject: [Haskell-cafe] Fwd: enhancing type classes with properties I´m just thinking aloud, but, because incorporating deeper mathematics concepts has proven to be the best solution for better and more flexible programming languages with fewer errors, I wonder if raising the type classes incorporating axioms can solve additional problems. At first sight it does: class Abelian a where (+) :: a -> a -> a property ((+))= a+b == b+a this permits: 1- safer polimorphism: I can safely reuse the operator + if the type and the property is obeyed. The lack of ability to redefine operators is a problem for DSLs that must use wreid symbols combinations with unknow meanings. To use common operators with fixed properties is very good. the same aplies for method names. 2- the compiler can use the axions as rewrite rules. 3- in debugging mode, it is possible to verify the axiom for each value a generated during execution. Thus, a generator is not needed like in quickcheck. The logic to quickcheck can be incorporated in the debugging executable. 3 guaranties that 1 and 2 are safe. a type class can express a relation between types, but it is not possible to define relation between relations. ============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ==============================================================================