Subject: Re: Good way to strip nulls from list ?
From: (Rob Warnock)
Date: 2000/04/07
Newsgroups: comp.lang.scheme
Message-ID: <8cjdok$qnvf$>
John Clonts  <> wrote:
|   2) what is letrec and how does it compare with define (below)

"Letrec" is "essential syntax" in R4RS Scheme ["library syntax" in R5RS]
for binding self-recursive or mutually-recursive expressions. All "internal
definitions" [a define within the body of a define/lambda/begin/let/let*/
letrec/do/etc.] are converted to equivalent "letrec" expressions (which may
then perhaps be expanded to more primitive forms, but that's another story).

R4RS allowed but did not require the implementation to support internal
definitions. R5RS requires them. [Some implementations even allow them
in positions other than the beginning of a "body", but this is non-standard
and should not be depended upon.]


Rob Warnock, 41L-955
Applied Networking
Silicon Graphics, Inc.		Phone: 650-933-1673
1600 Amphitheatre Pkwy.		PP-ASEL-IA
Mountain View, CA  94043