bugMIT/GNU Scheme - Bugs: bug #19535, Reduction of Lists: 'reduce'...


bug #19535: Reduction of Lists: 'reduce' reverses arguments

Submitted by:  None
Submitted on:  Fri 06 Apr 2007 04:18:32 AM UTC  
Category:  runtime Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Suboptimal behavior
Status:  Fixed Privacy:  Public
Assigned to:  None Originator Name:  Anton Davis
Originator Email:  -email is unavailable- Open/Closed:  Closed

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  Spam posted by annaanna1
Fri 06 Apr 2007 05:23:37 AM UTC, comment #1: 

This is a consequence of bringing MIT Scheme up-to-date with respect to the current quasi-standard for list libraries, SRFI 1 <http://srfi.schemers.org/srfi-1/srfi-1.html>, which was designed after MIT Scheme's built-in list library.  There is now a procedure which has the old semantics of REDUCE but with the name REDUCE-LEFT, although it's not yet in any released snapshot.

It's an annoying problem, and I have been working on a system that will eliminate this cluttering of a global environment with these overlapping names, but there are other tasks to be done first, such as preparing the C back end for release.

Taylor R. Campbell <riastradh>
Project Member
Fri 06 Apr 2007 04:18:32 AM UTC, original submission:  

The functions 'reduce-right', 'fold-left' and 'fold-right' work as described in the documentation, but 'reduce' produces incorrect results.

(reduce list '() '(1 2 3 4)) => (4 (3 (2 1))
(reduce - 0 '(1 2 3 4))      => 2


(list (list (list 1 2) 3) 4) => (((1 2) 3) 4)
(- (- (- 1 2) 3) 4)          => -8

It seems that 'reduce' reverses the order of its arguments in release 7.7.90.+.



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Carbon-Copy List
  • -email is unavailable- added by mhb (Updated the item)
  • -email is unavailable- added by mhb
  • -email is unavailable- added by riastradh (Posted a comment)

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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2013-05-30 mhb StatusNone => Fixed
        Open/ClosedOpen => Closed
        Carbon-Copy- => Added bug-mit-scheme@gnu.org
    2010-03-14 riastradh Carbon-CopyRemoved 77162 => -
    2008-07-09 riastradh Attached File#16056 => Removed
    2008-07-09 None Attached File- => Added valid_rss_80x15.png, #16056
    2007-04-06 riastradh CategoryNone => runtime
        Item GroupIncorrect behavior => Suboptimal behavior

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