[debbugs-tracker] bug#24080: closed (fold-left description in (rnrs lists) section of guile manual incorrect)

[GNU bug Tracking System]

Your message dated Thu, 04 Aug 2016 22:40:25 +0200
with message-id <address@hidden>
and subject line Re: bug#24080: fold-left description in (rnrs lists) section 
of guile manual incorrect
has caused the debbugs.gnu.org bug report #24080,
regarding fold-left description in (rnrs lists) section of guile manual 
incorrect
to be marked as done.

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24080: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=24080
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> --- Begin Message ---
>
>
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> Subject: 
>
> fold-left description in (rnrs lists) section of guile manual incorrect
>
>
>
>
> Date: 
>
> Tue, 26 Jul 2016 16:15:06 -0400
>
>
>
>
> The section on the (rnrs lists) library in the guile manual contains the 
> following:
>
> Scheme Procedure: fold-left combine nil list1 list2 …
> Scheme Procedure: fold-right combine nil list1 list2 …
>
>     These procedures are identical to the fold and fold-right procedures 
> provided by SRFI-1.
>
> In the case of fold-left and SRFI-1 fold, this is not correct; the order in 
> which the arguments are passed to the combine procedure is different. Compare:
>
> (let ((f (lambda (a b) (format #f "(f ~a ~a)" a b))))
>   (for-each
>    (lambda (fold)
>      (display (fold f "0" '(a b c d e)))
>      (format #t " ; ~s\n" (procedure-name fold)) )
>    (list (@ (rnrs lists) fold-left)
>          (@ (rnrs lists) fold-right)    ;same as srfi-1 fold-right
>          (@ (srfi srfi-1) fold)
>          (@ (srfi srfi-1) fold-right))))
>
> Output:
>
> (f (f (f (f (f 0 a) b) c) d) e) ; fold-left
> (f a (f b (f c (f d (f e 0))))) ; fold-right
> (f e (f d (f c (f b (f a 0))))) ; fold
> (f a (f b (f c (f d (f e 0))))) ; fold-right
>
> In the single-list case, fold-left can be thought of as applying f 
> left-associatively to the elements of the list.
> Moreover, in this case (fold f nil l) == (fold-left (lambda (x y) (f y x)) nil 
> l).
>
> (In the case of fold-right, both versions are identical).
>
>
>
> --- End Message ---
> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#24080: fold-left description in (rnrs lists) section of guile manual incorrect
>
>
>
>
> Date: 
>
> Thu, 04 Aug 2016 22:40:25 +0200
>
>
>
>
> User-agent: 
>
> Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)
>
>
>
>
> On Tue 26 Jul 2016 22:15, "Glenn Michaels" <address@hidden> writes:
>
> > The section on the (rnrs lists) library in the guile manual contains the 
> > following:
> >
> > Scheme Procedure: fold-left combine nil list1 list2 …
> > Scheme Procedure: fold-right combine nil list1 list2 …
> >
> >     These procedures are identical to the fold and fold-right procedures 
> > provided by SRFI-1.
>
> I believe this was fixed by
>
>   commit 498cd58cb43e0dde024ad3c62983def16a0c7ca9
>   Author: Andy Wingo <address@hidden>
>   Date:   Thu Jun 23 21:39:23 2016 +0200
>
>       Fix R6RS fold-left documentation
>       
>       * doc/ref/r6rs.texi (rnrs lists): Fix documentation of fold-left.
>
> Should be out in 2.1.4.
>
> Cheers,
>
> Andy
>
>
> --- End Message ---