Iterators should be widely used in rust, but currently their notation is quite limiting. Below are three points that I would suggest to consider for extension of the iterators notation.
The first point is the ability to specify the type of the iterator. I am not sure what would be the best notation for this, probably something like:
The second point is the ability to operate on floats, for instance:
The last point is regarding the exclusive upper bound. I agree this is convenient in some contests, because for instance
0..10 is similar to the typical C statement
for (i = 0; i < 10; i++). However it can be source of bugs in other contests, for instance numerical computation. For this I would suggest to add the notation
0:10 with inclusive upper bound, which is used by MATLAB and many other numerical computing languages.