Template constraints

[matovitch via Digitalmars-d]

Sorry for the mistakes in the above message (and in this one). I 
didnt gave earlier my personnal opinion on the matter but 
essentially if I like the syntax of type classes very much, you 
can do much more with templates constraint and D meta programming 
abilities...But you still have to fix some kind of pragmatic 
limit in the compile time introspection I think...