Jon Harrop  <jon@ffconsultancy.com> wrote:
+---------------
| Rob Warnock wrote:
| > William D Clinger  <cesura17@yahoo.com> wrote:
| > +---------------
| > | Proper tail recursion is not limited to self tail
| > | calls, but is about the asymptotic space efficiency
| > | achieved by implementing general tail calls without
| > | creating new continuations unnecessarily.  R5RS 3.5
| > | and R6RS 5.11 define proper tail recursion by
| > | reference to the formal definition in my PLDI 1998
| > | paper [3].
| > +---------------
| > 
| > It is this sort of terminological confusion that makes me
| > really, *really* wish that RxRS had instead used the term
| > "proper tail call optimization", since the latter encompasses
| > both the general case and the specific case of "tail recursion".
| > (*sigh*)
| 
| Indeed. Surely that nomenclature (which is what I had understood
| to be conventional) was around long before William's 1998 paper?
+---------------

It was around, and the extensive references in Clinger's paper
document that, but it was seldom (if ever) defined as to precisely
what it *meant*, especially in terms of the formal semantics.
That was the contribution of Clinger's PLDI 1998 paper, especially
defining it in terms of the "safe for space" criterion (which, as he
freely notes, is essentially the same definition as that proposed by
Morrisett & Harper, reference [MH97] in Clinger's paper). You should
actually read it before dismissing it so cavalierly.


-Rob

-----
Rob Warnock			<rpw3@rpw3.org>
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