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RE: tail recursion proposal

It seems a shame not to use Guy's humorous definition of tail pessimization 
(along with Kent's modification) in the write-up for the requirement of proper 
tail-recursion. It points out the tradeoff while nicely conveying the spirit of 
scheme's proper tail-recursion requirement.

Bruce Duba

"The effective substitution of some other continuation k2 for the continuation 
k in the call to p1 is called <I>tail call pessimization</I>.  This is an 
extremely detrimental pessimization because it effectively prevents the use of 
tail calls to implement iteration, a widely used and well-loved programming 
idiom in the Scheme language [that defeats the widely used and well-loved 
program idiom of stack debugging common to other languages].  Tail call 
pessimization will cause an iteration so programmed to accumulate unnecessary 
continuations; informally, they will unnecessarily ``consume stack''.

Implementations of Scheme are required to reliably detect function calls from a 
tail position and to avoid tail call pessimization."