Rust switches to external iteration

[Jonathan M Davis]

On Thursday, July 04, 2013 11:37:15 H. S. Teoh wrote:
> if a function
> only needs to iterate the range once, then it should only require an
> input range, nothing more.

Agreed, but it's freuently the case that an input range isn't enough, and even 
if it is for a particular function, odds are than the result of that function 
is going to need to be fed to another function which _does_ require more than 
an input range. And far too often, it's the case that people think that an 
input range is enough when in fact a forward range is required, but the 
implicit save that many ranges do makes it so that the function works without 
calling save much of the time, even though it really does need to save.

Whenever I have to deal with pure input ranges, I find it to be extremely 
annoying. The simple fact that you can't even save its state is just way too 
limiting for a lot of algorithms to be able to be implemented in any kind of 
sane way, if at all, and too much of Phobos becomes unavailable either because 
what it's trying to do just can't be done with an input range or because it 
would consume the range when you can't afford for it to be consumed.

- Jonathan M Davis