Till Varoquaux wrote:

> Typw inference in haskell is not decideable (nor is it in ocaml when
> using objects) and you have to provide some type information.

Huh? The only thing that is not decidable in Haskell's type system is  
polymorphic recursion. Apart from that you do not need any type  
annotations (except in order to get around Haskell's monomorphism  
restriction, but that is a different story).

> On top of breaking inference type cleases come at a high run tine
> cost.

Type classes do not break type inference. Just read Mark P. Jones's  
papers.

Regards
Wolfgang