I would also like to add that the module Smart::Comments also supports progress bars, like so:

use Smart::Comments;
foreach (@array) { ### Evaluating...           done
    # do something...
}
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I've read somewhere that its use was not recommended because, unlike the approach reviewed in the root node, it does source filtering. Although it might not be a guarantee of anything, I personally used it for my "progress bar" needs without a problem.