ASCII and Unicode lifespan (Was: Corrections to Glagolitic)

From: Hans Aberg (
Date: Tue May 17 2005 - 07:49:23 CDT

  • Next message: Peter Kirk: "Re: Corrections to Glagolitic"

    At 13:20 +0100 2005/05/17, Peter Kirk wrote:
    >>So if ASCII based software now switches to use say UTF-8 instead,
    >>which does not seems to be so difficult to achieve, the 25 year
    >>limit on active use may apply to that one, too.
    >Thank you, Hans. But I would suggest that ASCII is already obsolete,
    >in that almost no one still uses it. In practice they have long been
    >using supersets like any of the ISO-8859 variants or UTF-8. Of
    >course many users in practice restrict themselves largely to the
    >original ASCII subset. But I consider a standard which has been
    >supersetted in this way as no longer in active use.

    When designing a computer language, it is still natural to restrict
    to the ASCII subset. But in the theorem prover I am writing on, I
    just fed Flex with a UTF-8 .l file, editing it in a UTF-8 editor;
    there is a Unicode font (Code2001) that can display the characters I
    am interested in, and there is even a keyboard layout editor Ukelele
    (for Mac OS X) available. This seems to work just fine; there are no
    theoretical reasons for why it should not work. Currently I admit in
    the input, in parallel, ASCII and UTF-8 reserved names.

    This UTF-8 is still in parallel to the ASCII names; the language is
    still expressible via an ASCII only file. But if the right Unicode
    aware tools are in place, I tend to think that there is no need for
    admitting an ASCII only input. One might compare this with the
    situation of the C/C++ trigraphs, supplied in order to admit certain
    restricted character encodings, where compilers support that, but are
    more likely to have them turned off as a default compile option.

    So admitting more than one character set is probably just a bother.
    And I may zip out the ASCII keywords at a later stage. Then ASCII is
    truly out of active use.

       Hans Aberg

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