Question

import System.IO

makeGrid :: Int -> Int -> a -> [[a]]
makeGrid x y = replicate y . replicate x

startGame = do
putStrLn "Select a difficulty (1,2): "
difficulty <- getLine
|difficulty == '1' = makeGrid 3 3 False
|difficulty == '2' = makeGrid 5 5 False
|otherwise = putStrln "Wrong thing"
             some function            --start from beginning again

如你所见，我有一个函数makeGrid。我想在startGame中获取用户输入并根据用户输入调用makeGrid。如果可能的话，还要做一个while循环，我该怎么做？

Answer 1

{-# LANGUAGE LambdaCase #-}

import System.IO

playGame = do
  grid <- initializeGrid
  -- game code goes here

initializeGrid = do
  putStrLn "Select a difficulty (1,2): "
  getLine >>= \case -- "difficulty <- getLine" <newline> "case difficulty of" also ok
    "1" -> return $ makeGrid 3 3 False
    "2" -> return $ makeGrid 5 5 False
    _   -> do
      putStrln "Wrong thing"
      initializeGrid

makeGrid :: Int -> Int -> a -> [[a]]
makeGrid x y = replicate y . replicate x

如何接受用户输入并根据它们调用函数？

1 个答案: