I think it overlooked a correction: the signature of generation->either should be (generation->either obj objs ...).
(For the consistency with truth-either, it can be (generation->either obj fail-obj ...), but in that case the description needs to be edited accordingly.)
This is clearly an editorial oversight, and since the description is meaningless as it stands (it refers to arguments that are not given in the prototype) the second solution should be adopted. The first solution is technically a smaller change, but means that obj and objs have completely different semantics, which is confusing.
The same correction should be made.
And a typo in either-guard:
The syntactic analogue of exception-either.
The syntactic analogue of exception->either.
This should also be fixed.
Arthur, please apply 6430f90dc6b832d89e926ae4e6d300363e75b19b. I think no notification in the document is required.