my @array = ('aa'..'zz');
my @slice_idx = (6,13,42,66,69);
# Slice
my @slice = @array[@slice_idx];

my %slice_idx = map { $_ => 1 } @slice_idx;
my @invslice_idx = grep { ! exists $slice_idx{$_} } 0 .. $#array;
# Inverse slice.
my @invslice = @array[@invslice_idx];