#! perl -slw
use strict;
use List::Comprehensions;

sub expandDims {
    return unless ref $_[ 0 ] eq 'ARRAY';
    return [ 0 .. $#{ $_[ 0 ] } ], expandDims( $_[ 0 ][ 0 ] );
}


my $ref2D = [ map [ 0 .. 2 ], 0..3 ];
my $ref3D = [ map [ map [ 0..1 ], 0..2, ], 0..3 ];
my $ref4D = [ map [ map [ map [ 0..1 ], 0..2, ], 0..3 ], 0..4 ];
my $ref = ( $ref2D, $ref3D, $ref4D )[ rand 3 ];

comp1 {
    my $val = $ref;
    $val = $val->[ $_ ] for @_;
    printf "[%s] := %s\n", join('][', @_), $val;
} expandDims( $ref );