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This queue is for tickets about the Scalar-List-Utils CPAN distribution.

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Id: 1386
Status: resolved
Priority: 0/
Queue: Scalar-List-Utils

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Owner: Nobody in particular
Requestors: gbarr [...] pobox.com
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Date: Fri, 2 Aug 2002 16:45:07 +0100
From: Graham Barr <gbarr [...] pobox.com>
To: bug-Scalar-List-Utils [...] rt.cpan.org
Subject: [Fwd] addition to List::Util?
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----- Forwarded message from Sean O'Rourke <educated_foo@yahoo.com> ----- Date: Thu, 30 May 2002 15:17:44 -0700 (PDT) To: gbarr@pobox.com From: Sean O'Rourke <educated_foo@yahoo.com> Subject: addition to List::Util? Something I find useful (and frequently requested) is the ability to iterate over multiple lists in parallel. I think List::Util would be a good home for this, although my XS-fu is not strong enough to write a C version (and I'm not sure it would be worth it in any case). Anyways, here's the Perl version, named "zipwith" because that's what Haskell uses ("mapm" or "multimap" might be a better name). If you're so inclined, feel free to include it in some future version of List::Util. Great module, btw -- it's nice to have some more of the lispy list-manipulation functions pre-implemented in Perl. /s =item zipwith BLOCK LIST LIST must be a list of list references. Returns a list of the results of calling BLOCK with the the ith element of each list in LIST. Shorter lists are extended with undefined values. @foo = zipwith { sum @_ } [1,2,3], [4,5], [6] # @foo is (11, 7, 3) =cut sub zipwith(&@) { my $code = shift; return () unless @_; my $n = max (map { croak 'zipwith BLOCK LIST-OF-LISTS: not a list' unless ref $_ eq 'ARRAY'; $#{$_}; } @_); no warnings qw(uninitialized); my @ret; foreach my $i (0..$n) { push @ret, &$code(map { $_->[$i] } @_); } @ret; } Show quoted text
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