[Haskell-beginners] Type error when using splitOn function.

22 Feb 2017


      Hello.
I'm new to Haskell and this is the first time I use Data.Text module.
And using stack on OSX 10.12.3
I'm try several times, but fail. and I don't understand what error message
says.
How can I fix this?
Thank you a lot.

Code is

Main.hs :
module Main where
import Lib

main :: IO ()
main = do
        sam <- readSam
        rxDxData <- readCSV
        print $ makeRxDxList rxDxData

Lib.hs :
module Lib
--    ( someFunc
--    ) where
      where

import Data.Text as T
import Text.Regex.TDFA
import Prelude hiding (take, drop, map, lines)

type RowSAM = Text
type RowRxDx = Text

--makeRxDxList :: Functor f => f Text -> f [Text]
--makeRxDxList rowRxDx = fmap (\x -> splitOn (pack ",") x) rowRxDx  -- This
code pass a compile.
makeRxDxList rowRxDx = map (\x -> splitOn (pack ",") pack x) $ lines rowRxDx
(whole code is below...)

Error Message is
/Users/shaegis/Documents/Haskell/samChecker3/src/Lib.hs:25:35: error:
    • Couldn't match expected type ‘Char -> Char’
                  with actual type ‘[Text]’
    • The function ‘splitOn’ is applied to three arguments,
      but its type ‘Text -> Text -> [Text]’ has only two
      In the expression: splitOn (pack ",") pack x
      In the first argument of ‘map’, namely
        ‘(\ x -> splitOn (pack ",") pack x)’

/Users/shaegis/Documents/Haskell/samChecker3/src/Lib.hs:25:54: error:
    • Couldn't match expected type ‘Text’
                  with actual type ‘String -> Text’
    • Probable cause: ‘pack’ is applied to too few arguments
      In the second argument of ‘splitOn’, namely ‘pack’
      In the expression: splitOn (pack ",") pack x
      In the first argument of ‘map’, namely
        ‘(\ x -> splitOn (pack ",") pack x)’

/Users/shaegis/Documents/Haskell/samChecker3/src/Lib.hs:25:64: error:
    • Couldn't match expected type ‘Text’ with actual type ‘[Text]’
    • In the second argument of ‘($)’, namely ‘lines rowRxDx’
      In the expression:
        map (\ x -> splitOn (pack ",") pack x) $ lines rowRxDx
      In an equation for ‘makeRxDxList’:
          makeRxDxList rowRxDx
            = map (\ x -> splitOn (pack ",") pack x) $ lines rowRxDx
------------------------------------------------------------------------------------------------------
Lib.hs
module Lib
--    ( someFunc
--    ) where
      where

import Data.Text as T
import Text.Regex.TDFA
import Prelude hiding (take, drop, map, lines)

type RowSAM = Text
type SAM = [Text]
type Case = Text
type RowRxDx = Text
type RxDx = [Text]
type RxDxList = [[Text]]
type Rx = Text
type Dx = Text
type MediName = Text
type Message = Text
type Date = Text
type PtName = Text

--makeRxDxList :: Functor f => f Text -> f [Text]
--makeRxDxList rowRxDx = fmap (\x -> splitOn (pack ",") x) rowRxDx
makeRxDxList rowRxDx = map (\x -> splitOn (pack ",") pack x) $ lines rowRxDx

pickupMediName :: RxDx -> MediName
pickupMediName rxDx = rxDx !! 0

pickupDx :: RxDx -> Dx
pickupDx rxDx = rxDx !! 2

pickupRx :: RxDx -> Rx
pickupRx rxDx = rxDx !! 1

pickupPtName :: Case -> PtName
pickupPtName ptCase = take 3 $ drop 45 ptCase

pickupCaseDate :: Case -> Date
pickupCaseDate ptCase = take 8 $ drop (348 + 2) ptCase

isErrorRxDx :: Rx -> Dx -> Case -> Bool
isErrorRxDx rxCode dxCode ptCase =
    case isExistRx rxCode ptCase of
        True  -> if (isExistDx dxCode ptCase) then False else True
        False -> False

isExistDx :: Dx -> Case -> Bool
isExistDx dxCode ptCase = (unpack ptCase) =~ (unpack dxCode)

isExistRx :: Rx -> Case -> Bool
isExistRx rxCode ptCase = rxCode `isInfixOf` ptCase

splitIntoCase :: RowSAM -> SAM
splitIntoCase = splitOn $ pack "AH021"

readCSV :: IO Text
readCSV = pack <$> readFile
"/Users/shaegis/Documents/Haskell/samChecker3/RxDxData.csv"

readSam :: IO Text
readSam = pack <$> readFile
"/Users/shaegis/Documents/Haskell/samChecker3/BoHomUTF8.dat"

[Haskell-beginners] Type error when using splitOn function.

S. H. Aegis