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Tail Recursion in Common Lisp ???
- To: Fahlman@C.CS.CMU.EDU, Parker.es@XEROX.COM
- Subject: Tail Recursion in Common Lisp ???
- From: Bernard S. Greenberg <BSG@STONY-BROOK.SCRC.Symbolics.COM>
- Date: Thu, 17 Jul 86 10:53 EDT
- Cc: Common-Lisp@SU-AI.ARPA
- In-reply-to: <FAHLMAN.12223204543.BABYL@C.CS.CMU.EDU>
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
"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.