[r6rs-discuss] Unicode issues

From: Thomas Lord <lord>
Date: Tue, 28 Aug 2007 10:20:23 -0700

William D Clinger wrote:
>> 2. There are no explicit provisions for a limited repertoire of
>> characters, where resources are limited. It looks like all characters
>> must be supported.
>>
>
> Correct. That is one of the many absolute requirements
> of the R6RS that should not have been.
>


Moreover, R6 forbids the addition of characters which are
not Unicode scalar values. You may not limit the character
set, and you may not extend it, at least in the core language.


If you want to find a "design motif" that explains R6's char
and string types, I think you need look no further than to see
that they are more or less a direct transliteration of the way
scalar values and locale-independent string processing are defined
in the Unicode standard.

All of the higher-level constructs in Unicode (e.g., compound
characters, locale support) are founded (aka "defined in terms of")
the scalar value model -- so it is a straight exercise in transliteration
to make R6 libraries of those, given the core of this sort.

It is as if R6 were designed, in part, to be a domain-specific
language for the purpose of playing with a "pure" implementation
of the Unicode character model.

(This is, of course, a regression from lisp tradition and Scheme
tradition in which the character type was extensible and far more
abstract.)

-t
Received on Tue Aug 28 2007 - 13:20:23 UTC