Truly lazy ranges, transient .front, and std.range.Generator

[HaraldZealot via Digitalmars-d]

On Tuesday, 18 August 2015 at 19:37:47 UTC, Joseph Rushton 
Wakeling wrote:
>
> Yes, broadly like your example, although note that your version 
> won't handle multiple popFront() calls in succession without 
> any .front call in-between.

Good point! And you show acceptable solution.

The last your example I prefer to parametrize with alias to 
functions:

```d
mixin template LazyPopFront(alias frontImplementation, alias 
popFrontImplementation)
...
```
It gives more flexibility.


One that worries me, if someone start to make odd things like 
create shared instance of this range.