[r6rs-discuss] Unicode issues

From: Felix <pfr6rs>
Date: Tue, 28 Aug 2007 19:32:50 -0400

On Aug 28, 2007, at 6:49 PM, John Cowan wrote:

> Thomas Lord scripsit:
>
>> Per R6, the Scheme character type is a set of exactly 1,112,064
>> distinct
>> values, no more, no less.
>
> That is to say, 1,112,064 character objects that are distinguishable
> by char= (and a fortiori by eql?). There is nothing to prevent an
> implementer from introducing more character objects distinguishable
> by finer-grained predicates. For example, if you wanted to add bits
> attributes, you could do so, providing such procedures as (bits-
> char ch),
> (char-with-bits ch bits), and (bits-char= ch1 ch2).

Note that R6RS specifies that two characters are eqv? if they are char=?

Therefore it really isn't in the spirit of R6RS to introduce finer
equivalence predicates on characters than char=?

-Felix
Received on Tue Aug 28 2007 - 19:32:50 UTC