GNU bug report logs - #20375
doc. error in v 2.0.11, Section 7.6.2.5

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Matt Wette <mwette <at> alumni.caltech.edu>
To: bug-guile <at> gnu.org
Cc: mwette <at> alumni.caltech.edu
Subject: doc. error in v 2.0.11, Section 7.6.2.5
Date: Sun, 19 Apr 2015 19:20:57 -0700

The reference manual for guile 2.0.11 has an error in  Section 7.6.2.5 on rnrs lists.  The statement "identical to the fold ..." is not quite correct.  The section says:

fold-left combine nil list1 list2 . . . [Scheme Procedure] fold-right combine nil list1 list2 . . . [Scheme Procedure] These procedures are identical to the fold and fold-right procedures provided by SRFI-1. See Section 7.5.3.5 [SRFI-1 Fold and Map], page 556, for documentation. 


In section 7.5.3.5, the manual says:
(fold cons ’() ’(1 2 3)) [...] (3 2 1)


But, fold-left does not work like fold: the arguments to the procedure to fold-left are reversed with respect to fold:.

 guile i2.0.11correctly gives the following:

(fold-left cons '() '(1 2 3)) => (((() . 1) . 2) . 3)

(fold-left xcons '() '(1 2 3)) => (3 2 1)


 Matt

Message #10 received at 20375-done <at> debbugs.gnu.org (full text, mbox):

From: Andy Wingo <wingo <at> pobox.com>
To: Matt Wette <mwette <at> alumni.caltech.edu>
Cc: 20375-done <at> debbugs.gnu.org
Subject: Re: bug#20375: doc. error in v 2.0.11, Section 7.6.2.5
Date: Thu, 23 Jun 2016 22:07:26 +0200

On Mon 20 Apr 2015 04:20, Matt Wette <mwette <at> alumni.caltech.edu> writes:

> The reference manual for guile 2.0.11 has an error in Section 7.6.2.5
> on rnrs lists.  The statement "identical to the fold ..." is not quite
> correct.  The section says:
>
> fold-left combine nil list1 list2 . . . [Scheme Procedure] fold-right
> combine nil list1 list2 . . . [Scheme Procedure] These procedures are
> identical to the fold and fold-right procedures provided by
> SRFI-1. See Section 7.5.3.5 [SRFI-1 Fold and Map], page 556, for
> documentation.
>
>
> In section 7.5.3.5, the manual says:
> (fold cons ’() ’(1 2 3)) [...] (3 2 1)
>
>
> But, fold-left does not work like fold: the arguments to the procedure to fold-left are reversed with respect to fold:.
>
>  guile i2.0.11correctly gives the following:
>
> (fold-left cons '() '(1 2 3)) => (((() . 1) . 2) . 3)
>
> (fold-left xcons '() '(1 2 3)) => (3 2 1)

Gah, you're right.  What a mess.  Fixed in master, will backport
soonish.

Andy

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