It wouldn't surprise me. My memory is of two things: - I was into E in the 90s and this idea was new to me then. - I vaguely remember reading someone online m

It wouldn't surprise me. My memory is of two things: - I was into E in the 90s and this idea was new to me then. - I vaguely remember reading someone online mentioning that E was the known prior art to Hettinger's reinvention of this. But this dim memory is not reliable, so I wanted to check it. And yeah, storing the hashcode is a technique I saw in the wild earlier than I saw the insertion-ordered hashtable.