You might also take a look at Array::Unique. Its only dependencies are Perl 5, but it is not a core module itself. I only found out about it recently but from what I've used of it, it seems to work well. I agree with princepawn that it would be nice if Perl had a built-in uniq function because this problem does tend to come up fairly often and it would make sense not to have to rely on an extra module.