Issue ALIST-NIL

[Kim A. Barrett <IIM@ECLA.USC.EDU>]

    As an actual "real-world" example of the second usage described under "Cost
to Users", my boss mentioned that he worked out an implementation of Baker's
Shallow Binding scheme (1) that depended on permitting Nil to be an ignored
alist entry.  He admits that it could have been written using an alternative
mechanism like that described in the proposal.  However, doing so might ugly,
since it might be necessary to go to extra trouble to reuse that special cell
rather than gratuitously consing up a new one all the time.

kab

(1) "Shallow Binding in Lisp 1.5", Henry G. Baker, Jr., Communications of the
ACM, July 1978, Volume 21, Number 7, page 565.

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