Storing values in an N x N grid











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I am trying to write a program to store/display a grid of size N x N with cells containing either a 1 or a 0 in preparation for further computation:



module Board where

import Data.List as List

data CellState = One | Zero deriving (Eq, Ord)

data Cell = Cell {cellPos :: (Int, Int), cellState :: CellState} deriving (Eq, Ord)

type Board = [Cell]

instance Show CellState where
show One = "1"
show Zero = "0"

instance Show Cell where
show (Cell c x) = show (c,x)

genPositions :: Int -> [(Int, Int)]
genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

genCellState :: Int -> CellState
genCellState 0 = Zero
genCellState 1 = One

newBoard :: Int -> [Int] -> Board
newBoard i [x] = [Cell (round $ sqrt(fromIntegral i), round $ sqrt(fromIntegral i)) (genCellState x)]
where positions = genPositions $ round $ sqrt(fromIntegral i)
newBoard i (x : xs) = [Cell (positions!!(i - 1 - length xs)) (genCellState x)] ++ newBoard i xs
where positions = genPositions $ round $ sqrt(fromIntegral i)


What improvements can I make to this, both in terms of good practises and performance? I don't like Board being a list of Cells. I posted this on Stack Overflow by accident (have since deleted it) and someone recommended changing type Board = [Cell] to newtype Board = Board { getBoard :: Array (Int,Int) CellState } but I'm not too familiar with arrays in Haskell so not sure how this would work exactly. From what I have read they apply a function to the elements in the range [Int..Int] and return a list of tuples with the input and output.










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    I am trying to write a program to store/display a grid of size N x N with cells containing either a 1 or a 0 in preparation for further computation:



    module Board where

    import Data.List as List

    data CellState = One | Zero deriving (Eq, Ord)

    data Cell = Cell {cellPos :: (Int, Int), cellState :: CellState} deriving (Eq, Ord)

    type Board = [Cell]

    instance Show CellState where
    show One = "1"
    show Zero = "0"

    instance Show Cell where
    show (Cell c x) = show (c,x)

    genPositions :: Int -> [(Int, Int)]
    genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

    genCellState :: Int -> CellState
    genCellState 0 = Zero
    genCellState 1 = One

    newBoard :: Int -> [Int] -> Board
    newBoard i [x] = [Cell (round $ sqrt(fromIntegral i), round $ sqrt(fromIntegral i)) (genCellState x)]
    where positions = genPositions $ round $ sqrt(fromIntegral i)
    newBoard i (x : xs) = [Cell (positions!!(i - 1 - length xs)) (genCellState x)] ++ newBoard i xs
    where positions = genPositions $ round $ sqrt(fromIntegral i)


    What improvements can I make to this, both in terms of good practises and performance? I don't like Board being a list of Cells. I posted this on Stack Overflow by accident (have since deleted it) and someone recommended changing type Board = [Cell] to newtype Board = Board { getBoard :: Array (Int,Int) CellState } but I'm not too familiar with arrays in Haskell so not sure how this would work exactly. From what I have read they apply a function to the elements in the range [Int..Int] and return a list of tuples with the input and output.










    share|improve this question
















    bumped to the homepage by Community 32 mins ago


    This question has answers that may be good or bad; the system has marked it active so that they can be reviewed.

















      up vote
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      down vote

      favorite









      up vote
      1
      down vote

      favorite











      I am trying to write a program to store/display a grid of size N x N with cells containing either a 1 or a 0 in preparation for further computation:



      module Board where

      import Data.List as List

      data CellState = One | Zero deriving (Eq, Ord)

      data Cell = Cell {cellPos :: (Int, Int), cellState :: CellState} deriving (Eq, Ord)

      type Board = [Cell]

      instance Show CellState where
      show One = "1"
      show Zero = "0"

      instance Show Cell where
      show (Cell c x) = show (c,x)

      genPositions :: Int -> [(Int, Int)]
      genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

      genCellState :: Int -> CellState
      genCellState 0 = Zero
      genCellState 1 = One

      newBoard :: Int -> [Int] -> Board
      newBoard i [x] = [Cell (round $ sqrt(fromIntegral i), round $ sqrt(fromIntegral i)) (genCellState x)]
      where positions = genPositions $ round $ sqrt(fromIntegral i)
      newBoard i (x : xs) = [Cell (positions!!(i - 1 - length xs)) (genCellState x)] ++ newBoard i xs
      where positions = genPositions $ round $ sqrt(fromIntegral i)


      What improvements can I make to this, both in terms of good practises and performance? I don't like Board being a list of Cells. I posted this on Stack Overflow by accident (have since deleted it) and someone recommended changing type Board = [Cell] to newtype Board = Board { getBoard :: Array (Int,Int) CellState } but I'm not too familiar with arrays in Haskell so not sure how this would work exactly. From what I have read they apply a function to the elements in the range [Int..Int] and return a list of tuples with the input and output.










      share|improve this question















      I am trying to write a program to store/display a grid of size N x N with cells containing either a 1 or a 0 in preparation for further computation:



      module Board where

      import Data.List as List

      data CellState = One | Zero deriving (Eq, Ord)

      data Cell = Cell {cellPos :: (Int, Int), cellState :: CellState} deriving (Eq, Ord)

      type Board = [Cell]

      instance Show CellState where
      show One = "1"
      show Zero = "0"

      instance Show Cell where
      show (Cell c x) = show (c,x)

      genPositions :: Int -> [(Int, Int)]
      genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

      genCellState :: Int -> CellState
      genCellState 0 = Zero
      genCellState 1 = One

      newBoard :: Int -> [Int] -> Board
      newBoard i [x] = [Cell (round $ sqrt(fromIntegral i), round $ sqrt(fromIntegral i)) (genCellState x)]
      where positions = genPositions $ round $ sqrt(fromIntegral i)
      newBoard i (x : xs) = [Cell (positions!!(i - 1 - length xs)) (genCellState x)] ++ newBoard i xs
      where positions = genPositions $ round $ sqrt(fromIntegral i)


      What improvements can I make to this, both in terms of good practises and performance? I don't like Board being a list of Cells. I posted this on Stack Overflow by accident (have since deleted it) and someone recommended changing type Board = [Cell] to newtype Board = Board { getBoard :: Array (Int,Int) CellState } but I'm not too familiar with arrays in Haskell so not sure how this would work exactly. From what I have read they apply a function to the elements in the range [Int..Int] and return a list of tuples with the input and output.







      array haskell






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      edited Nov 22 '17 at 1:00









      Jamal

      30.2k11115226




      30.2k11115226










      asked Nov 22 '17 at 0:54









      user6731064

      61




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      bumped to the homepage by Community 32 mins ago


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          By defining r = round . sqrt . fromIntegral, newBoard fits on the screen. positions doesn't appear to be used in newboard's first case. Half the code disappears if we interpret Cell as ((Int, Int), Int). newBoard's first case can be pushed one recursion call deeper, mapping to instead of [x] to the current right hand side. [_] ++ _ ~> _ : _. positions is only used once, therefore I inline it.



          type Cell = ((Int, Int), Int) -- (position, state)

          genPositions :: Int -> [(Int, Int)]
          genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

          r = round . sqrt . fromIntegral

          newBoard :: Int -> [Int] -> [Cell]
          newBoard i =
          newBoard i (x : xs) = (genPositions (r i)!!(i - 1 - length xs), x) : newBoard i xs


          Successive elements of the list returned by genPositions and xs are zipped together; zip captures this pattern. i is now not needed in its non-rooted form and I recommend changing the interface to take N as an argument instead. Non-square arguments can currently crash !! anyway. genPositions is only used once, therefore I inline it.



          type Cell = ((Int, Int), Int) -- (position, state)

          newBoard :: Int -> [Int] -> [Cell]
          newBoard n = zip $ liftA2 (,) [0..n-1] [0..n-1]


          For type Board = Array (Int, Int) Int, Data.Array allows newBoard n = listArray ((0,0),(n-1,n-1)).






          share|improve this answer





















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            By defining r = round . sqrt . fromIntegral, newBoard fits on the screen. positions doesn't appear to be used in newboard's first case. Half the code disappears if we interpret Cell as ((Int, Int), Int). newBoard's first case can be pushed one recursion call deeper, mapping to instead of [x] to the current right hand side. [_] ++ _ ~> _ : _. positions is only used once, therefore I inline it.



            type Cell = ((Int, Int), Int) -- (position, state)

            genPositions :: Int -> [(Int, Int)]
            genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

            r = round . sqrt . fromIntegral

            newBoard :: Int -> [Int] -> [Cell]
            newBoard i =
            newBoard i (x : xs) = (genPositions (r i)!!(i - 1 - length xs), x) : newBoard i xs


            Successive elements of the list returned by genPositions and xs are zipped together; zip captures this pattern. i is now not needed in its non-rooted form and I recommend changing the interface to take N as an argument instead. Non-square arguments can currently crash !! anyway. genPositions is only used once, therefore I inline it.



            type Cell = ((Int, Int), Int) -- (position, state)

            newBoard :: Int -> [Int] -> [Cell]
            newBoard n = zip $ liftA2 (,) [0..n-1] [0..n-1]


            For type Board = Array (Int, Int) Int, Data.Array allows newBoard n = listArray ((0,0),(n-1,n-1)).






            share|improve this answer

























              up vote
              0
              down vote













              By defining r = round . sqrt . fromIntegral, newBoard fits on the screen. positions doesn't appear to be used in newboard's first case. Half the code disappears if we interpret Cell as ((Int, Int), Int). newBoard's first case can be pushed one recursion call deeper, mapping to instead of [x] to the current right hand side. [_] ++ _ ~> _ : _. positions is only used once, therefore I inline it.



              type Cell = ((Int, Int), Int) -- (position, state)

              genPositions :: Int -> [(Int, Int)]
              genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

              r = round . sqrt . fromIntegral

              newBoard :: Int -> [Int] -> [Cell]
              newBoard i =
              newBoard i (x : xs) = (genPositions (r i)!!(i - 1 - length xs), x) : newBoard i xs


              Successive elements of the list returned by genPositions and xs are zipped together; zip captures this pattern. i is now not needed in its non-rooted form and I recommend changing the interface to take N as an argument instead. Non-square arguments can currently crash !! anyway. genPositions is only used once, therefore I inline it.



              type Cell = ((Int, Int), Int) -- (position, state)

              newBoard :: Int -> [Int] -> [Cell]
              newBoard n = zip $ liftA2 (,) [0..n-1] [0..n-1]


              For type Board = Array (Int, Int) Int, Data.Array allows newBoard n = listArray ((0,0),(n-1,n-1)).






              share|improve this answer























                up vote
                0
                down vote










                up vote
                0
                down vote









                By defining r = round . sqrt . fromIntegral, newBoard fits on the screen. positions doesn't appear to be used in newboard's first case. Half the code disappears if we interpret Cell as ((Int, Int), Int). newBoard's first case can be pushed one recursion call deeper, mapping to instead of [x] to the current right hand side. [_] ++ _ ~> _ : _. positions is only used once, therefore I inline it.



                type Cell = ((Int, Int), Int) -- (position, state)

                genPositions :: Int -> [(Int, Int)]
                genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

                r = round . sqrt . fromIntegral

                newBoard :: Int -> [Int] -> [Cell]
                newBoard i =
                newBoard i (x : xs) = (genPositions (r i)!!(i - 1 - length xs), x) : newBoard i xs


                Successive elements of the list returned by genPositions and xs are zipped together; zip captures this pattern. i is now not needed in its non-rooted form and I recommend changing the interface to take N as an argument instead. Non-square arguments can currently crash !! anyway. genPositions is only used once, therefore I inline it.



                type Cell = ((Int, Int), Int) -- (position, state)

                newBoard :: Int -> [Int] -> [Cell]
                newBoard n = zip $ liftA2 (,) [0..n-1] [0..n-1]


                For type Board = Array (Int, Int) Int, Data.Array allows newBoard n = listArray ((0,0),(n-1,n-1)).






                share|improve this answer












                By defining r = round . sqrt . fromIntegral, newBoard fits on the screen. positions doesn't appear to be used in newboard's first case. Half the code disappears if we interpret Cell as ((Int, Int), Int). newBoard's first case can be pushed one recursion call deeper, mapping to instead of [x] to the current right hand side. [_] ++ _ ~> _ : _. positions is only used once, therefore I inline it.



                type Cell = ((Int, Int), Int) -- (position, state)

                genPositions :: Int -> [(Int, Int)]
                genPositions x = [ (a,b) | a <- [0..(x-1)], b <- [0..(x-1)] ]

                r = round . sqrt . fromIntegral

                newBoard :: Int -> [Int] -> [Cell]
                newBoard i =
                newBoard i (x : xs) = (genPositions (r i)!!(i - 1 - length xs), x) : newBoard i xs


                Successive elements of the list returned by genPositions and xs are zipped together; zip captures this pattern. i is now not needed in its non-rooted form and I recommend changing the interface to take N as an argument instead. Non-square arguments can currently crash !! anyway. genPositions is only used once, therefore I inline it.



                type Cell = ((Int, Int), Int) -- (position, state)

                newBoard :: Int -> [Int] -> [Cell]
                newBoard n = zip $ liftA2 (,) [0..n-1] [0..n-1]


                For type Board = Array (Int, Int) Int, Data.Array allows newBoard n = listArray ((0,0),(n-1,n-1)).







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 22 '17 at 23:49









                Gurkenglas

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                2,728511






























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