Re: Motion 46 -- Vincent's objections
On 2013-07-20 01:03:43 -0400, Michel Hack wrote:
> Regarding interval notation in right-to-left locales,
> Vincent Lefèvre replied to me:
> > > I know that numeric literals are witten in the same order as for
> > > left-to-right scripts, but what about the order of bounds in the
> > > pair that denotes an interval? Is the low bound the first or the
> > > leftmost element?
> >
> > The first, but I would say that the full interval literal would be
> > written left-to-right.
>
> Huh? I meant "first" in the direction of the script; if the whole
> interval is written left-to-right, then the upper bound would be
> first when reading right-to-left. Or did Vincent imply that the
> entire interval literal be considered a single numeric entity?
>
> > Otherwise the first character would be "]", not "[".
>
> Right -- the outermost character. That's the generic way
> of describing bracketing constructs. The "otherwise" is
> not justified as this would be the case regardless of the
> ordering of upper vs lower bound.
I think you should ask some expert in right-to-left scripts.
Actually it seems that the mirroring of "[" and "]" would be
done automatically, but I'm not sure. On
http://www.unicode.org/reports/tr9/
it is said:
L4. A character is depicted by a mirrored glyph if and only if
(a) the resolved directionality of that character is R, and
(b) the Bidi_Mirrored property value of that character is true.
* The Bidi_Mirrored property is defined by Section 4.7,
Bidi Mirrored—Normative of [Unicode]; the property values are
specified in [UCD].
* This rule can be overridden in certain cases; see HL6.
For example, U+0028 left parenthesis—which is interpreted in the
Unicode Standard as an opening parenthesis—appears as “(” when its
resolved level is even, and as the mirrored glyph “)” when its
resolved level is odd. Note that for backward compatibility the
characters U+FD3E (﴾) ORNATE LEFT PARENTHESIS and U+FD3F (﴿) ORNATE
RIGHT PARENTHESIS are not mirrored.
> > One may also wonder a BOM would be accepted as the first character...
>
> Bill Of Materials???
Byte Order Mark
--
Vincent Lefèvre <vincent@xxxxxxxxxx> - Web: <http://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)