@jwakely, @CaseyCarter: have you got a general policy that iterator type parameters should be called I? In principle this change looks good, but maybe we can record such conventions somewhere for posterity?

@hewillk Please rebase?

@jwakely, @CaseyCarter Ping :-)

We're inconsistent across the entire library, I think we use I, It, Iter and Iterator in various places. In Ranges we do consistently use I: constraints clarify the meaning of names so we don't need descriptive placeholders. The traditional class InputIterator becomes input_iterator I in Ranges templates.

EDIT: As the use of concepts expands into the rest of the Library, it's likely that we'll continue this practice of short-and-simple placeholders.

have you got a general policy that iterator type parameters should be called I?

No, but what Casey said.