Tail Recursion in Common Lisp ???

[Bernard S. Greenberg <BSG@STONY-BROOK.SCRC.Symbolics.COM>]

    Date: Wed, 16 Jul 1986  15:47 EDT
    From: "Scott E. Fahlman" <Fahlman@C.CS.CMU.EDU>


	ok, ok, my question was sloppily worded.  does the definition of Common
	Lisp require that all implementations have tail recursion optimization ?

    No.  It has even been suggested that the current definition does not 
    allow tail-recursion optimization -- that's an issue we have to settle
    soon, and I hope that we'll be able to work out a solution in which this
    is allowed.

    -- Scott 

"8/9 of this can of worms is below the surface".  If the spec -allows-
tail-recursion optimization, and "my" implementation "supports"
tail-recursion, then "I" can, and most likely -will-, write a
"tail-recursive" program, which is theoretically portable, but in fact,
will blow the stack of most certified implementations that do not
"support" tail-recursion, and is thus, subtly, not portable.