Can someone explain and solve the error message I am getting in my vignereCode function

Question

import Data.Char
import Prelude
import System.IO

encode :: Char -> Int
encode x = ord x - ord 'A'

decode :: Int -> Char
decode x = chr (x + ord 'A')

shift :: (Int -> Int -> Int) -> Int -> Char -> Char
shift f x ch = decode $ f (encode ch) x `mod` 26

rightShift :: Int -> Char -> Char
rightShift = shift (-)

leftShift :: Int -> Char -> Char
leftShift = shift (-)

encodeString :: String -> [Int]
encodeString str = map encode str

vignereString :: String -> String -> String
vignereString secret plain = take len $ cycle secret 
  where len = length $ concat

vignereCode :: String -> String -> [Int]
vignereCode secret plain = encodeString $ vignereString

encrypt :: String -> String -> String
encrypt secret plain = 
  zipWith rightShift code plainNoSpace 
  where code = vignereCode secret plain
        plainNoSpace = concat $ words plain

decrypt :: String -> String -> String
decrypt secret cipher = zipWith leftShift code cipherNoSpace
  where code = vignereCode secret cipher
        cipherNoSpace = concat $ words cipher

---

error message: main.hs:28:43: error:
    * Couldn't match type `String -> String -> String' with `[Char]'
      Expected type: String
        Actual type: String -> String -> String
    * Probable cause: `vignereString' is applied to too few arguments
      In the second argument of `($)', namely `vignereString'
      In the expression: encodeString $ vignereString
      In an equation for `vignereCode':
          vignereCode secret plain = encodeString $ vignereString
   |
28 | vignereCode secret plain = encodeString $ vignereString
   |                                           ^^^^^^^^^^^^^
exit status 1

Answer 1

In vignereCode you are not passing any argument to vignereString. I think you want to compose encodeString and vignereString instead to apply the former to the latter.

vignereCode :: String -> String -> [Int]
vignereCode = encodeString . vignereString