Rewrite of Data.Char library?

Ahn, Ki Yung kyagrd at
Fri Oct 23 03:01:29 EDT 2009

Colin Paul Adams wrote:
>>>>>> "Ahn" == Ahn, Ki Yung <kyagrd at> writes:
>     Ahn> Just a follow-up to add, and my suggestions.  Lowercase and
>     Ahn> Uppercase problem seems not to be solvable, since in some
>     Ahn> languages like German sz doesn't have a good definition for
>     Ahn> an uppercase letter.
> You just follow the Unicode default foldings.
> Note that these foldings are not inverses of each other - intuition is
> misplaced here.


The real problem I think, as I've mentioned in the second posting is 
that isAlpha is neither backward compatible nor conforms to the Haskell 
98 report.  I suggest that we revert isAlpha back to the definition of 
Haskell 98 report and just add a new function called isLetter for what 
current implementation of Data.Char.isAlpha is doing.  If this is 
controversial, I think there wouldn't be any problem that at least 
isAlpha in Char, the good old Haskell 98 standard libary module, should 
conform to the Haskell 98 definition, which is either isUpper or isLower.

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