[web-devel] Data.Word8 (word8 library)
Kazu Yamamoto ( 山本和彦 )
kazu at iij.ad.jp
Fri Sep 21 05:11:11 CEST 2012
> Ignoring this, I think I can summarize:
> - Data.ByteString.Char8 has no performance penalty: "w2c" uses
> "unsafeChr" which is a no-op, and GHC.Word has a RULES pragma making the
> "fromIntegral" also free (it's a narrow8Word#)
> - for some reason GHC is generating worse code for the Word8 versions of
> toLower than it is for the Char equivalents
> - consequently, there seems to be no reason to use the word8 library:
> not only is it not faster, it's actually a pessimization.
My dictionary does not have the word "pessimization". Would you explain
what do you want to say with other words?
Anyway, my understanding from this thread is:
- Data.ByteString.Char8 does not have performance penalty. So, we can
use the character literal (e.g. 'H') with it for code readability.
- But the utility functions in Data.Char is slow because it handles
Unicode. So, we need faster utility functions specialized to Char.
Is this correct? Should I implement the char8 library (or include
Data.Char8 in the word8 library)?
I know that Greg dislikes to have extra libraries but I think that
sharing utility functions is a good thing.
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