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Fahlman's new new sequence proposal, and an issue of policy

    Date: Monday, 22 February 1982  02:50-EST
    From: MOON at SCRC-TENEX

    mumble-IF-NOT is equally as useful as mumble-IF, if you look at how they
    are used.  This is because the predicate argument is rarely a lambda, but
    is typically some pre-defined function, and most predicates do not come in
    complementary versions.  (Myself, I invariably write such things with
    LOOP, so I don't have a personal axe to grind.)

Another possibility is to define a function composition operator.
Then you'd do
	(mumble-IF ... (COMPOSE #'NOT #'SYMBOLP) ...)
instead of
	(mumble-IF ... (LAMBDA (X) (NOT (SYMBOLP X))) ...)
This is nicer because it avoids introducing the extra name X.
(Maybe the #'s wouldn't be needed?)