Working with ranges is an interesting idea, and comparisons to std::ranges::find might encounter obstacles. I presume that the OP was talking about returning an optional value given the key. This presumes an associative container. Why limit this to associative containers? A generic version can search a std::vector as well as a std::set or boost::unordered_map You just need to dispatch to either container.find or fallback to std::find I am not too familiar with ranges, is there an "associative range" concept? I do like the default value idea though, thanks for that :) Having the optional return type you get the default for free: find(...).value_or() I'm not too sure about supporting ranges: The hypothetical find function would return an optional reference. So we have the footgun of getting dangling references already when someones does `find(build_map(), key)` We can avoid that by deleting the overload for rvalues but i guess for ranges we might not be able to easily detect an underlying temporary.