$ perl -le'
my @array = 1 .. 8;
print "@array";
@array = map { $array[ $_ + @array / 2 ], $array[ $_ ] } 0 .. $#array 
+/ 2;
print "@array";
'
1 2 3 4 5 6 7 8
5 1 6 2 7 3 8 4
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