concepts and interfaces

[Craig Black]

This may sound a little retarded, but wouldn't making concepts obligatory 
make generic programming more complex and hence more difficult?  In my 
opinion this may do more harm than good.  A huge appeal of generic stuff in 
D is that it's easier to work with than the C++ stuff.  More powerful, yes, 
but also easier.  IMO this is very important.

On the other hand, this increased complexity is a burden only on the one who 
is developing the generic library.  It's appeal is that it makes life easier 
for the developer that uses the generic library because that developer gets 
more intelligent error messages.  This makes generic libraries more 
attractive to the average developer.

While I'm not opposed to these features, they don't make me terribly 
excited.  With all the other features on the queue, I don't forsee anything 
like this getting into D.

-Craig