There is no array "@hash1" there is only the hash "%hash1".

This is called a hash slice , and in a quirk of perl syntax uses the @ sigil instead of %

my %foo; @foo{ 'hash', 'slices' } = ( 'use', 'curly braces' );

my @bar; @bar[ 1,2,3,4 ] = ( 'array', 'slices', 'use', 'square brackets' );

Say it with me:

{ 'hashes', 'are', 'curly', 'ones' }

[ 'arrays', 'are', 'square' ]

( 'lists are round' )