Re: [Scheme-reports] digit-value

[John Cowan <cowan@x>]

Pierpaolo Bernardi scripsit:

> string->number and read accepting as numbers all characters satisfying
> the current char-numeric? would be crazy.
> 
> Think roman numerals, just to take a simple example we all know about.
> Assuming the I are the right unicode character for the roman numeral 1:

The Roman-numeral characters (which are only present for backward
compatibility with certain other character sets) aren't decimal digits,
and therefore R7RS `char-numeric?` returns #f on them.  So things aren't
as bad as that: all the decimal digits are used in exactly the same way,
only the shapes differ from European digits.

Here is the complete list of scripts that have their own digits (sometimes
only in older texts; modern texts use the European style):

Arabic (two flavors, one for Arabic langauge, one for Persian and Urdu
languages), N'ko, Devanagari, Bengali, Gurmukhi, Gujarati, Oriya, Tamil,
Telugu, Kannada, Malayalam, Thai, Lao, Tibetan, Myanmar (two flavors,
one for Myanmar language, one for Shan language), Khmer, Mongolian, Limbu,
New Tai Lue, Tai Tham (two flavors, secular and ecclesiastical), Balinese,
Sundanese, Lepcha, Ol Chiki, Vai, Saurashtra, Kayah Li, Javanese, Cham,
Meetei Mayek, Osmanya, Brahmi, Sora Sompeng, Chakma, Sharada, Takri.

In addition, there is a set of fullwidth European digits (same shape,
but the size of Chinese characters), and the following sets of specially
fonted digits for mathematical use only:  math bold, math double-struck,
sans-serif, sans-serif bold, monospace.


-- 
I am expressing my opinion.  When my            John Cowan
honorable and gallant friend is called,         cowan@x
he will express his opinion.  This is           http://www.ccil.org/~cowan
the process which we call Debate.                   --Winston Churchill

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