We did that because it was the only option at the time. It was not ideal solution. 

On Wed, Jan 19, 2022, 9:39 AM Peter Dimov via SG7 <sg7@lists.isocpp.org> wrote:
David Rector wrote:
> I either cannot find or don’t have access to the revised paper, so apologies if
> this was discussed therein, but: can you comment on the choice to return a
> span instead of a non-random-access range object?  (I.e. provide a begin() and
> an end(), but no size(), operator[](size_t), etc.?)

That's what the Lock3 implementation does if I'm not mistaken.

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