Re: [web-devel] Data.Word8 (word8 library)

Here are the methods in question: -- | Conversion between 'Word8' and 'Char'. Should compile to a no-op.w2c :: Word8 -> Char#if !defined(__GLASGOW_HASKELL__)w2c = chr . fromIntegral#elsew2c = unsafeChr . fromIntegral#endif{-# INLINE w2c #-}-- | Unsafe conversion between 'Char' and 'Word8'. This is a no-op and-- silently truncates to 8 bits Chars > '\255'. It is provided as-- convenience for ByteString construction.c2w :: Char -> Word8c2w = fromIntegral . ord{-# INLINE c2w #-} They should both be harmless, according to the docs. 2012/9/20 Johan Tibell

On Thu, Sep 20, 2012 at 10:41 AM, Kazu Yamamoto wrote:

...

Why do people use Data.ByteString.Char8? I guess that there are two reasons:

- There are no standard utility functions for Word8 such as "isUpper" - Numeric literal (e.g 72 for 'H') is not readable

The Char8 module was added so that it's easier to work with protocols that mix binary and ASCII data, such as HTTP.

Note that Word8 is represented using a full machine word, just like Char, so you're unlikely to get any performance improvements from Word8 in this case (unless GHC fails to simplify e.g. calls to 'ord' and 'chr' in places).

-- Johan

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