Constraints

["İbrahim Gökhan]

Allways we have some ways to do somethings.
The question is: which is better, easier and understandable.
I think my proposal is better.


> And these could certainly use some library sugar. How about 
> this:
>
> template isJustInputRange(R) {
>     enum bool isJustInputRange = isInputRange!R && 
> !isForwardRange!R;
> }

If we add for example isBufferedInputRange, we have to change 
isJustInputRange too. It's not a general solution.