On Friday 24 June 2005 14:28, Andreas Rossberg wrote:
Ralf Lammel wrote:
I would like to add a peer-reviewed clear reference to the OOHaskell paper about the red herring that you mention. I don't have such a reference. May I kindly ask you to offer a few for selection?
Off-hand, I recall a paper by Martin Odersky and the Scala people discussing their approach to the Expression Problem, and a related paper by Jacques Garrigue, where he proposes to solve it using OCaml's polymorphic variants. Both should be easy to dig up with Google, and probably contain further pointers.
Inspired by this post I read some of the available papers on Scala (among them the above). I find Scala very, very interesting. However, I am quite curious how the inventors of Scala managed to to write 100's of dense pages of papers, citing influences from 10's of other languages... ...and at the same time completely fail to even once mention Eiffel, which shares a lot of interesting features with Scala. The paper "An overview of the Scala Programming Language" lists allogether 10 Authors. Have really none of those 10 authors ever heard of Eiffel and its famous attitude of "we are using multiple inheritance more often than loops"? Ok, Eiffel has a few holes in its type-system, doesn't naturally integrate with Java/.Net, and doesn't support XML directly. And Eiffel does not support deferred types in class definitions. But: IIRC, Eiffel was the first OO-language that almost completely solved the multiple-inheritance problem, providing solutions very similar to ones in Scala. For instance, mixin-type inheritance is easily possible in Eiffel. Also, Eiffel provides the same kind of automatic replacement of deferred (expected) methods and attributes with concrete (implemented) ones. In a few places, Eiffel is even more general. For instance, in Eiffel you can even inherit two concrete methods with the same name. In order to resolve the name conflict you just rename one of them in your derived class. Furthermore, Eiffel does not distinguish between class and trait (although maybe the distinction is a good idea) without placing any restrictions on classes. Another nice feature of Eiffel is that access can be restricted in a very fine grained way, i.e. for each single method (or group of methods) you can give a list of classes that are allowed to call this method. Ben