Function Cell Follow-up

[Jonathan A Rees <JAR@MC.LCS.MIT.EDU>]

    Date: Mon, 24 Feb 86 15:56 EST
    From: David C. Plummer <DCP at SCRC-QUABBIN.ARPA>

    Is tail recursion REQUIRED of Scheme implementations, or is just in all
    the papers because it is easy to do in most Scheme implementations.

It's absolutely as essential as garbage collection.  (If you argue
against one you must argue against the other.)  See page 8 of the MIT AI
memo 848 (the "revised revised report") and the abstract of memo 452
(the "revised report").  Also note that no mechanism other than function
call is supplied to implement iteration, and it would be absurd to limit
the number of iterations of a loop to a function of the space available
for stack.

(It was no easier or harder to do in "most scheme implementations" than
in implementations of any other language, except by virtue of having
been designed for; I don't quite understand the remark.)