Readme for csv-conduit-0.6.2.1

README

CSV Files and Haskell

CSV files are the de-facto standard in many cases of data transfer, particularly when dealing with enterprise application or disparate database systems.

While there are a number of csv libraries in Haskell, at the time of this project's start, there wasn't one that provided all of the following:

Over time, people created other plausible CSV packages like cassava. The major benefit from this library remains to be:

This package

csv-conduit is a conduit-based CSV parsing library that is easy to use, flexible and fast. It leverages the conduit infrastructure to provide constant-space operation, which is quite critical in many real world use cases.

For example, you can use http-conduit to download a CSV file from the internet and plug its Source into intoCSV to stream-convert the download into the Row data type and do something with it as the data streams, that is without having to download the entire file to disk first.

Author & Contributors

Introduction

Speed

While fast operation is of concern, I have so far cared more about correct operation and a flexible API. Please let me know if you notice any performance regressions or optimization opportunities.

Usage Examples

Example #1: Basics Using Convenience API

{-# LANGUAGE OverloadedStrings #-}

import Data.Conduit
import Data.Conduit.Binary
import Data.Conduit.List as CL
import Data.CSV.Conduit
import Data.Text (Text)

-- Just reverse te columns
myProcessor :: Monad m => Conduit (Row Text) m (Row Text)
myProcessor = CL.map reverse

test :: IO ()
test = runResourceT $ 
  transformCSV defCSVSettings 
               (sourceFile "input.csv") 
               myProcessor
               (sinkFile "output.csv")

Example #2: Basics Using Conduit API

{-# LANGUAGE OverloadedStrings #-}

import Data.Conduit
import Data.Conduit.Binary
import Data.CSV.Conduit
import Data.Text (Text)

myProcessor :: Conduit (Row Text) m (Row Text)
myProcessor = undefined

-- Let's simply stream from a file, parse the CSV, reserialize it
-- and push back into another file.
test :: IO ()
test = runResourceT $ 
  sourceFile "test/BigFile.csv" $= 
  intoCSV defCSVSettings $=
  myProcessor $=
  fromCSV defCSVSettings $$
  sinkFile "test/BigFileOut.csv"