http://www.perlmonks.org?node_id=1001547


in reply to @array elements multiplication with another array elements.

Here's another example using pairwise from the lovely List::MoreUtils package...

use List::MoreUtils qw( pairwise );

my @array1 = (3,4,6,5,8);
my @array2 = (2,2,4,5,1);

my @mults = pairwise { $a * $b } @array1, @array2;
print "@mults\n";

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perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

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Re^2: @array elements multiplication with another array elements.
by grizzley (Chaplain) on Oct 31, 2012 at 07:39 UTC
    Wow, how can pairwise tell where the end of 1st array is? There was always the problem feature that regardless whether you write 
    my @array1 = (3,4,6,5,8);
my @array2 = (2,2,4,5,1);

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    or 
    my @array1 = (3,4,6,5,8,2,2,4);
my @array2 = (5,1);

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    using it with coma always results in flattened list: 
    @array1,@array2

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    is equivalent to 
    (3,4,6,5,8,2,2,4,5,1)

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    and yet pairwise deals with it: 
    c:\>perl -le "use List::MoreUtils qw/pairwise/; @a=(1..5);@b=(11..15);
+ print for pairwise {$a+$b} @a, @b"
12
14
16
18
20

c:\>perl -le "use List::MoreUtils qw/pairwise/; @a=(1..5, 11,12);@b=(1
+3..15); print for pairwise {$a+$b} @a, @b"
14
16
18
4
5
11
12

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      It uses a prototype of &\@\@. That means the two arrays get implicitly turned into arrayrefs by the Perl parser. The body of the sub just sees a coderef and two arrayrefs - not a flattened list. See perlsub.

      perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'
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[d/l]
        That's true! Wow, thanks, first example of prototypes being useful 
        c:\>perl -le "sub f(\@\@) { print 'array ', ++$cnt ,': ', join ' ', @$
+_ for @_ } @a=(1..5, 11,12);@b=(13..15); f @a, @b"
array 1: 1 2 3 4 5 11 12
array 2: 13 14 15

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