[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Naive T Design Questions Addendum

    Date: Thu, 14 Apr 88 21:59:49 EDT
    From: James J. Hunt <jjh at ll-vlsi.arpa>

    7. Why not separate the concept of () and no entry in tables?

(I think you mean #F, not (), since absence of entry is indicated by a
false return from table-entry.)  This is easily simulated given the
existing primitives, so it would be an unnecessary complication.  E.g.
it would require the addition of something like a TABLE-HAS-ENTRY?
predicate, and it would require the addition of a separate procedure for
deleting entries (currently you can just store a #F).

    P.S.  The IF THEN ELSE macro would be more efficient if
	  (= 1 (length rest)), is replaced by (not (cdr rest)).

You are dealing with lists, not booleans, so I think you want NULL?, not
NOT here.