Head and tail make sense for persistent lists in functional languages with value semantics, yes. The intrusive, mutable, doubly-linked loops with reference sem

Head and tail make sense for persistent lists in functional languages with value semantics, yes. The intrusive, mutable, doubly-linked loops with reference semantics under discussion are quite different. Although all entries behave identically in the structure itself, one of them is _used_ differently, as a standalone anchor point, while the others are embedded in the list's "elements".