1FastPermute(3)        User Contributed Perl Documentation       FastPermute(3)
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NAME

6       Algorithm::FastPermute - Rapid generation of permutations
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SYNOPSIS

9         use Algorithm::FastPermute ('permute');
10         my @array = (1..shift());
11         permute {
12             print "@array\n";         # Print all the permutations
13         } @array;
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DESCRIPTION

16       Algorithm::FastPermute generates all the permutations of an array. You
17       pass a block of code, which will be executed for each permutation. The
18       array will be changed in place, and then changed back again before
19       "permute" returns. During the execution of the callback, the array is
20       read-only and you'll get an error if you try to change its length. (You
21       can change its elements, but the consequences are liable to confuse you
22       and may change in future versions.)
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24       You have to pass an array, it can't just be a list. It does work with
25       special arrays and tied arrays, though unless you're doing something
26       particularly abstruse you'd be better off copying the elements into a
27       normal array first.
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29       It's very fast. My tests suggest it's four or five times as fast as
30       Algorithm::Permute's traditional interface.  If you're permuting a
31       large list (nine or more elements, say) then you'll appreciate this
32       enormously. If your lists are short then Algorithm::Permute will still
33       finish faster than you can blink, and you may find its interface more
34       convenient.
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36       In fact, the FastPermute interface (and code) is now also included in
37       Algorithm::Permute, so you may not need both. Enhancements and bug
38       fixes will appear here first, from where (at Edwin Pratomo's
39       discretion) they'll probably make their way into Algorithm::Permute.
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41       The code is run inside a pseudo block, rather than as a normal
42       subroutine. That means you can't use "return", and you can't jump out
43       of it using "goto" and so on. Also, "caller" won't tell you anything
44       helpful from inside the callback. Such is the price of speed.
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46       The order in which the permutations are generated is not guaranteed, so
47       don't rely on it.
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EXPORT

50       The "permute" function is exported by default.
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AUTHOR

53       Robin Houston, <robin@kitsite.com>
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55       Based on a C program by Matt Day.
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SEE ALSO

58       Algorithm::Permute
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61       Copyright (c) 2001-2008, Robin Houston. All Rights Reserved.  This
62       module is free software. It may be used, redistributed and/or modified
63       under the same terms as Perl itself.
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67perl v5.34.0                      2021-07-22                    FastPermute(3)
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