You can use map() to iterate over the array. You can use this to build a hash that has only unique elements:

my @a = (0, 1, 1, 2, 3, 4, 5, 5, 5, 6);
my %unique;

map { $unique{$_} = 1 } @a;

my @a_unique = keys %unique;
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Above is untested, as always.

If you want to put the data back in sorted order, change the last line to:

my @a_unique = sort { $a <=> $b } keys %unique;

I can't really get more specific without knowing what exactly you are doing, but this should give you some ideas.