Why aren't Ranges Interfaces?

[Ali Çehreli via Digitalmars-d-learn]

On 06/26/2015 11:37 AM, Jack Stouffer wrote:

 > easier if the different types of Ranges where
 > just interfaces that you could inherit from.

If you think you need polymorphic interfaces, the next chapter talks 
about inputRangeObject():

 
http://ddili.org/ders/d.en/ranges_more.html#ix_ranges_more.polymorphism,%20run-time

Ali