std.range.iota enhancement: supporting more types (AKA issue 10762)

[Francesco Cattoglio]

On Saturday, 28 December 2013 at 13:58:40 UTC, Jakob Ovrum wrote:
> On Saturday, 28 December 2013 at 12:16:32 UTC, Joseph Rushton 
> Wakeling wrote:
>> Are you sure that's going to work if the iota covers a leap 
>> year? :-)
>
> How would it fail? std.datetime does a good job with leap years 
> AFAIK.

Yes it does, the catch is:
2012, Jan, 1 + "365 days") = 2012, Dec, 31
because 2012 is a leap year. If you compute "back = end - 
duration", you are asserting the user will always enter correct 
bounds. This is fine for trivial intervals, but iota won't be 
usable anywhere else.
It's always the same "issue": you have to compute the last 
element inside iota, you should never rely on the user giving you 
ideal inputs.