streamly-cassava: CSV streaming support via cassava for the streamly ecosystem

[ bsd3, library, streaming ] [ Propose Tags ]

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Dependencies base (>=4.7 && <5), bytestring, cassava, exceptions, mtl, streamly [details]
License BSD-3-Clause
Copyright 2019 Richard Warfield
Author Richard Warfield
Category Streaming
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Source repo head: git clone
Uploaded by rwarfield at 2019-09-23T12:42:35Z
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Last success reported on 2019-09-23 [all 1 reports]


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Stream CSV data in/out using Cassava. Adapted from streaming-cassava.

For efficiency, operates on streams of strict ByteString chunks (i.e. IsStream t => t m ByteString) rather than directly on streams of Word8. The chunkStream function is useful for generating an input stream from a handle.

Example usage:

import Streamly
import qualified Streamly.Prelude as S
import Streamly.Csv (decode, encode, chunkStream)
import System.IO
import qualified Data.Csv as Csv
import qualified Data.ByteString as BS
import Data.Vector (Vector)

main = do
  h <- openFile "testfile.csv" ReadMode
  let chunks = chunkStream h (64*1024)
      recs = decode Csv.HasHeader chunks :: SerialT IO (Vector BS.ByteString)
  withFile "dest.csv" WriteMode $ \ho ->
    S.mapM_ (BS.hPut ho) $ encode Nothing recs