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Re: case mappings

This page is part of the web mail archives of SRFI 75 from before July 7th, 2015. The new archives for SRFI 75 contain all messages, not just those from before July 7th, 2015.

Thomas Bushnell BSG <tb@xxxxxxxxxx> writes:

> Michael Sperber <sperber@xxxxxxxxxxxxxxxxxxxxxxxxxxx> writes:
>> For my applications, the case mappings defined in the draft are plenty
>> useful---they're sure useful well beyond ASCII.  Restricting them to
>> ASCII would make them very significantly less useful to me.  (What
>> with me being a German an all.  And BTW, no, the eszet issue is not
>> usually a problem in practice---it sure doesn't keep the case mappings
>> from being useful.)
> Your applications are useful *for German* maybe.... but that doesn't
> mean that the code you write, thinking only of your case, will work
> where the locale is different and more serious problems arise.

I have expressed myself poorly: If I want my code to behave in a
locale-specific way, then I'll use procedures that respect locale.
Ditto for full string-to-string case-mapping in a locale-independent
manner.  In other words, I need to indicate in my source code what I
want.  Sometimes I want exactly the case mapping the current SRFI
draft has---I *don't* want any of the others.

> You are quite right that this is a hard problem.  [...] 
> Case mapping is not a character-to-character function, it is a
> string-to-string function.
> Once you learn that, everything else becomes trivial.

I don't know what you think will become trivial.  Not much I can think
of.  Even implementing the UnicodeDate.txt case mappings is not
trivial to do efficiently---which is why we'll provide a reference
implementation for those pretty soon.

> Scheme has a system for numeric procedures that works automagically
> for systems that want really fancy stuff.

You're talking to the wrong person here: The fanciness in the R5RS
arithmetic often does the wrong thing.  Which is why people need to be
able to indicate what they want.  So this is a pretty good parallel to
the case mapping.

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla