[Haskell-cafe] C++ class = neutered (haskell class + haskell existential)

[Bulat Ziganshin]

Hello John,

Friday, August 18, 2006, 5:16:45 AM, you wrote:

> There is a major difference though, in C++ (or java, or sather, or c#,
> etc..) the dictionary is always attached to the value, the actual class
> data type you pass around. in haskell, the dictionary is passed
> separately and the appropriae one is infered by the type system.

your letter is damn close to that i wrote in
http://haskell.org/haskellwiki/OOP_vs_type_classes
although i mentioned not only pluses but also drawbacks of type
classes: lack of record extension mechanisms (such at that implemented
in O'Haskell) and therefore inability to reuse operation
implementation in an derived data type, lack of downcasting mechanism
(which bites me all the way), requirement to rebuild dictionaries in
polymorphic operations what is slow enough

i will put your letter there and later use it to build up the final
description, ok?



-- 
Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com