I'm not the grandparent poster, but one classic problem with STL iterators is that they always have to come in pairs. If you think about it, most STL algorithm

I'm not the grandparent poster, but one classic problem with STL iterators is that they always have to come in pairs. If you think about it, most STL algorithms don't really work on iterators, they work on ranges that happen to be defined by pairs of iterators. That makes it hard to compose operations, makes it hard to work with infinite streams, and makes it possible to screw up and write something like std::transform(v1.begin(), v2.end()). Have a look at Alexandrescu's work on ranges in D for a more modern exploration of the same concept.