Re: Character properties

From: Roozbeh Pournader (
Date: Sat Sep 23 2000 - 02:22:20 EDT

On Thu, 21 Sep 2000, Marcin 'Qrczak' Kowalczyk wrote:

> > I disagree with the isDigit case, simply because my main language,
> > Persian, uses alternate digits when written.
> Do they form numbers in the same way as ASCII digits?

Yes. The rules are exactly the same.

> Does Unicode character database provide a way to tell which digits
> form numbers in this way (decimal, "big Endian")?

General Category = Nd means decimal digit. I think it's always big-endian.

> Do you think that they (and digits from other languages) should
> be recognized as numbers in sources for programming languages that
> generally accept foreign letters in identifiers? (I don't know what
> Haskell gurus would say for that.)

I'm not in a position to recommend for or against them in program sources,
but they should be accepted as number forms for manual data entry.

> What about isOctDigit and isHexDigit?

Persian tradition uses European digits for Hexadecimal numbers, but for
Octal, Persian digit forms are sometimes used.

> Haskell provides digitToInt and intToDigit which currently deal with
> ASCII digits and hexadecimal "digits" A..F a..f. If isDigit accepted
> foreign digits, it would make sense to extend digitToInt to convert
> them too. But obviously not intToDigit.

intToDigit should look at the locale to select the preferred digit form,
I think.


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