Missing and desired sequence function.

[Skef Wholey <Wholey@C.CS.CMU.EDU>]

    Date: Thursday, 12 November 1987  01:09-EST
    From: Bob Kanefsky <Kanef at SPAR.SLB.COM>

    [...] later I realized I wanted it [the BEST function]
    to return the position as well as the element; [...]

Following the lead of FIND, POSITION, and perhaps even COUNT, we could
add a few new functions: FIND-BEST, POSITION-BEST (I think BEST-POSITION
sounds nicer, though), and COUNT-BEST.  This gives a picture of "BEST"
functions having a kind of orthagonalilty with the -IF and -IF-NOT forms
of these functions; indeed, the argument lists of these forms would be
identical to those of the -IF and -IF-NOT functions.

Also note that functions of this sort should take a :FROM-END keyword
(defaulting to NIL), so that one has control over which "best" item is
selected.

--Skef