[r6rs-discuss] [Formal] FIND delivers an ambiguous value

From: Nils M Holm <holm>
Date: Wed Nov 1 13:54:09 2006

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This message is a formal comment which was submitted to formal-comment_at_r6rs.org, following the requirements described at: http://www.r6rs.org/process.html
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Name: Nils M Holm
Mail: holm_at_t3x.org
Type of issue: Defect
Priority: Major
R6RS component: Libraries
Version: 5.91
Summary: FIND delivers an ambiguous value
Description:
The FIND procedure described on page 63 can deliver an ambiguous
return value when applied to a list of booleans:
(find not '(#f)) => #f
(find not '(#t)) => #f
Proposed improvement: return the tail of the sublist beginning
with the first member satisfying the predicate:
(find not '(#t #f #t)) => (#f #t)
      (find not '(#f)) => (#f)
      (find not '(#t)) => #f
This modification would not only eliminate the ambiguity described
above but also make FIND more compatible to MEMBER and friends.
-- 
Nils M Holm <holm_at_t3x.org> -- http://t3x.org/nmh/
Received on Wed Nov 01 2006 - 05:35:09 UTC

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