Except there is the issue of efficiency (see my other post above). Representing a string of characters which all happen to lie within the ASCII range as an untagged byte string allows the byte-oriented regex engine to be used.

It's a very similar idea to using machine words to hold integers up to a certain value, and then switching to a different representation for bignums. It doesn't make a difference to correctness, but it does make a difference to performance.

In reply to Re^2: Behaviour of Encode::decode_utf8 on ASCII by jbert
in thread Behaviour of Encode::decode_utf8 on ASCII by jbert

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