contravariant argument types: wanna?

[Lutger]

Andrei Alexandrescu wrote:

... 
> I am considering discussing all of the above in detail in TDPL, but I am
> afraid that some refugees from other languages will be shocked.

Please, it's much more important to write a good book than to avoid possibly  
offending the sensibilities of potential readers. Besides, anymore willing 
to take a risk with D will surely be open to learning something new.