I think they wanted to preserve the meaning of the existing two value types. The naming is still bad, though, because it's inconsistent. For example, why should

I think they wanted to preserve the meaning of the existing two value types. The naming is still bad, though, because it's inconsistent. For example, why should 'xvalue' belong to 'generalized lvalue' when it also belongs to 'rvalue'? Aren't 'l' and 'r' supposed to be opposites on the same dimension (movability)? Here's a suggestion in retrospect: | ivalue | pvalue --------------------- lvalue | ilvalue | (plvalue) rvalue | irvalue | prvalue The current naming is confusing exactly because 'lvalue' should be a supertype in one dimension, just like 'rvalue', and not a subtype (here: 'ilvalue'). I think they took this shortcut because 'plvalue' doesn't really exist, but it's still inconsistent. Let's not even talk about 'xvalue' (here: 'irvalue').