[arunc]

OP's point was about auto being littered in documentation and not in the code itself.

Having auto is a boon for certain design aspects. As system level programming language D offers everything in betterC mode. Of course it can offer more. But a small community can do only so much.

[aldacron]

It's not "littered" in the documentation for anyone who understands the basics of D's ranges. auto is the correct choice here. Range functions are lazy, meaning they are almost always used in a chain of function calls that ends in something like `.array` to get a concrete type -- an array in this case. At no point in that process do you care about the actual return type of any of those functions.