Re: [boost] [optional] operator<(optional<T>, T) -- is it wrong?

On Wed, Nov 26, 2014 at 4:49 PM, Gavin Lambert wrote:

But why do you want to have optional keys anyway? When does it make sense to have a single value attached to an empty key? It's rare for a dictionary type to permit null keys in any language.

I think this is a good point. Has anyone reading this list every actually used std::map?