Re: [Haskell-cafe] String to Double conversion in Haskell

Because normally, Prelude.read covers this. Don's link is the most efficient, but you can also do (read . ByteString.unpack $ bytestring) :: Double to get a Double from a printed representation of most numbers. 2008/8/24 Daryoush Mehrtash :

I am curious to understand the logic, the "Haskell Think", here. Why is it that the byteString only supports conversion to int.

daryoush On Sun, Aug 24, 2008 at 2:23 PM, Don Stewart wrote:

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dmehrtash:

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I am trying to convert a string to a float. It seems that Data.ByteString library only supports readInt. After some googling I came accross a possibloe implementation: [1]http://sequence.svcs.cs.pdx.edu/node/373

Use the bytstring-lexing library,

http://hackage.haskell.org/cgi-bin/hackage-scripts/package/bytestring-lexing

Which provides a copying and non-copying lexer for doubles,

readDouble :: ByteString -> Maybe (Double, ByteString) unsafeReadDouble :: ByteString -> Maybe (Double, ByteString)

-- Don

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