On Thu, Apr 20, 2006 at 10:32:37AM +1000, Donald Bruce Stewart wrote:
> ashley:
> > Donald Bruce Stewart wrote:
> >
> > > Interface:
> > > http://www.cse.unsw.edu.au/~dons/fps/Data.FastPackedString.html
> >
> > Given that FastString turns out to be an array of Word8, why are you using
> > Char at all?
>
> Convenience. Some historical legacy from darcs. And others have
> contributed patches specifically to add more Word8 support.
I think the biggest barrier to using Word8 operations on String-like
types is the Read/Show instance for Word8, which works like for other
Word types:
Prelude Data.Word> map (toEnum . fromEnum) "Haskell" :: [Word8]
[72,97,115,107,101,108,108]
Maybe we should introduce a Char8 type, or something like that, which
would have the nice Stringy presentation?
There is also a problem with literals. How about solving it by adding
a Num-like Character class? Consider:
Prelude> :t 1
1 :: (Num t) => t
Prelude> :t "abc"
"abc" :: CharAscii c => [c]
Prelude> :t "aąbcć"
"aąbcć" :: CharUnicode c => [c]
or even:
Prelude> :t "aąbcć"
"aąbcć" :: CharacterPolish c => [c]
;-)
And a String class would allow typing FastPackedString literals directly.
Best regards
Tomasz
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