my @array = map { LISTS => [ map [], 1..$length ] }, 1..$arr_len;

##</code><code>##

my @array = map { 'foo' => $_ }, 1..3;    # ok

my @array = map { $_ => 'foo' }, 1..3;    # not ok: 'syntax error at ..., near "},"'

##</code><code>##

my @array = map +{ $_ => 'foo' }, 1..3;   # ok