Re^3: -> Is Optional ?

[Athanasius]

The line

my @a = [ 1, 4, 9, 16 ];  # squares

creates an anonymous array with 4 elements, and assigns a reference to this anonymous array — i.e., a single, scalar value — to be the first (and only) element of the named array @a.

I suspect that parentheses were intended rather than square brackets:

my @a = ( 1, 4,  9, 16 );  # squares
my @b = ( 1, 8, 27, 64 );  # cubes
my @c = ( \@a, \@b );      # two arrays

and then the rest of the original code behaves as intended.

Hope that helps,