CODEWITHSUNDEEP
haskell
trolle
trolle

Reputation: 11

how to remove the quotation mark in string

I'm really new in Haskell. perhaps this is a simple question for the master coder. I want to remove the quotation mark outside the string. such as "A1" to A1.

I tried my best to solve this problem. but it doesn't work. I already used read :: Read a => String -> a, id function, and regular expression.

initialGuess :: ([Pitch],GameState)
initialGuess = (startGuess, GameState (chords))
      where startGuess = ["A1", "B1", "C1"] 
      standard = [[n, o] | n <- ['A'..'G'], o <- ['1'..'3']]  <br/>
      chords = [[a,b,c] | a <- standard, b <- standard, c <-  
               standard, a /= b, b /= c, a /= c]

initialGuess aim to takes no input arguments.And returns a pair of an initial guess and a game state. Running this code I can get

["A1","B1","C1"],GameState [["A1","A2","A3"],["A1","A2","B1"],["A1","A2","B2"],["A1","A2","B3"],["A1","A2","C1"]................["A1","A2","C2"],["A1","A2","C3"],["A1","A2","D1"],["A1","A2","D2"],["A1","A2","D3"]]

however, I want to remove these quotation marks such as

[A1,B1,C1],GameState [[A1,A2,A3],[A1,A2,B1],[A1,A2,B2],[A1,A2,B3],[A1,A2,C1]................[A1,A2,C2],[A1,A2,C3],[A1,A2,D1],[A1,A2,D2],[A1,A2,D3]]

Upvotes: 1

Views: 357

Answers (1)

Bob Dalgleish
Bob Dalgleish

Reputation: 8227

If all you are trying to do is make the states prettier, you can provide your own display function:

-- |Display a list of strings without quotation marks
showLStr :: [String] -> String
showLStr p  = "[" ++ intercalate "," p ++ "]"

The intercalate function puts the "," between each element of the list of strings.

showLStr ["A1", "A2", "A3"]

should display as

[A1,A2,A3]

Edit: Now you can use showLStr to display the game state:

showGameState :: GameState -> String
showGameState (GameState chords) =
  "GameState [" ++ (intercalate "," $ map showLStr chords) ++ "]"

-- |Make GameState "Show"-able
instance Show GameState where
  show = showGameState

showGuess :: ([Pitch],GameState) -> String
showGuess (pitch, gameState) = showLStr pitch ++ ", " ++ show gameState

Upvotes: 1

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