lens-csv

[ bsd3, library, unclassified ] [ Propose Tags ]

Please see the README on GitHub at https://github.com/ChrisPenner/lens-csv#readme


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Versions [RSS] 0.1.0.0, 0.1.1.0
Change log ChangeLog.md
Dependencies base (>=4.7 && <5), bytestring, cassava, lens [details]
License BSD-3-Clause
Copyright Chris Penner
Author Chris Penner
Maintainer christopher.penner@gmail.com
Home page https://github.com/ChrisPenner/lens-csv#readme
Bug tracker https://github.com/ChrisPenner/lens-csv/issues
Source repo head: git clone https://github.com/ChrisPenner/lens-csv
Uploaded by ChrisPenner at 2020-02-02T02:08:27Z
Distributions LTSHaskell:0.1.1.0, NixOS:0.1.1.0, Stackage:0.1.1.0
Downloads 926 total (15 in the last 30 days)
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Status Docs uploaded by user
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Readme for lens-csv-0.1.0.0

[back to package description]

lens-csv

A lensy layer on top of Cassava which affords streaming, traversable, CSV parsing.

Currently experimental (but working). Looking to improve error handling soon, currently parse failures are simply passed over by the traversals.

Example:

>>> import Data.ByteString.Lazy as BL
>>> myCsv <- BL.readFile "./data/simple.csv"
>>> myCsv ^.. namedCsv . taking 2 rows . column @String "state_code" 
[ "NY"
, "CA"
]

>>> myCsv ^.. namedCsv . taking 2 rows . _NamedRecord @(M.Map String String)
[ fromList [("population","19540000"), ("state_code","NY")]
, fromList [("population","39560000"), ("state_code","CA")]
]

-- For csv files without headers
>>> myCsv ^.. csv . taking 2 rows . _Record @[String]
[ ["state_code", "population"]
, ["NY"        , "19540000"]
]

-- 'column' infers whether it's a named or unnamed csv and accepts the appropriate index type (either ByteString or Int)
>>> myCsv ^.. csv . rows . column @Int 1
[19540000,39560000]

-- Use traversals to edit cells 'in-place' (add 1337 to California's population)
>>> BL.putStrLn $ myCsv & namedCsv . row 1 . column @Int "population" +~ 1337
state_code,population
NY,19540000
CA,39561337