Khaled,
Thank you for the link. The normalization methods were already discussed, specifically here:
Where the problem of "how big" is ä is discussed. The answer being that this is one symbol, because the Unicode Consortium decided that it is also its own standalone character. From the thread:
I'll give you an example. What would you want ⍴,'ä' to be?
Right now, that could return either 1 or 2 depending on whether the ä was using the precomposed character (U+00E4) or the combining mark (U+0061, U+0308). Visually, these are identical, and generally you'd expect them to compare equal.
In Unicode, the comparison of equivalent (but with different characters) strings are done by performing a normalisation step prior to comparison. There are 4 different types of normalisation, with different behaviour.
Now, the ä character has a precomposed form in Unicode, and if you couple that with the NFC normalisation form, you'd get the above _expression_ to return 1.
So I'm not sure why the allowance was made for ä as well as other certain characters, but not for other things (under-bar characters) that face similar representation issues.
-------- Original Message --------
Subject: Re: APL Under-bar Characters
From: Khaled Hosny <[email protected]>
Date: Sun, August 16, 2015 8:17 am
To: [email protected]
Cc: [email protected]
On Sun, Aug 16, 2015 at 07:35:17AM -0700, [email protected] wrote:
> Hello Unicode Mailing List,
>
> There is significant discussion about the problems of adding capital letters
> with individual under-bars in this mailing list for GNU APL.
>
> http://lists.gnu.org/archive/html/bug-apl/2015-08/msg00050.html
>
> Pretty much it adds up to the following problem:
>
> The string length functionality would view an 'A' code point combined with an
> '_' code point as an item that has two elements, while something that looks
> like 'A' Should be atomic, and return a length of one.
I think what you need is better “character” counting [1], rather than
new precomposed characters.
Regards,
Khaled
1. http://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries
