我的程序似乎無限運行，我不確定它在哪裏不能繼續

Question

我一直在使用I/O寫入Haskell中的文件，但它只是坐在那裏運行，沒有結束產品。

main :: IO() 
main = do 
    hawkID <- getLine 
    let text = "module Operations where\nimport " ++ hawkID ++ "\n\nsample :: (" ++ hawkID ++ "a)\nsample = B\n\ 
                         \size :: (" ++ hawkID ++ " a) -> Int\nsize x = 0\n\n\ 
                         \depth :: (" ++ hawkID ++ " a) -> Int\ndepth x = 0\n\n\ 
                         \dropN :: (" ++ hawkID ++ " a) -> (" ++hawkID ++ " a)\ndropN x = x\n\n\ 
                         \countB :: (" ++ hawkID ++ " a) -> Int\ncountB x = 0\n\ 
                         \ltoB :: (" ++ hawkID ++ " a) -> (" ++ hawkID ++ " b)\nltoB x = B\n\n\ 
                         \toString :: (" ++ hawkID ++ " a) -> String\ntoString x = \"\"\n\n\ 
                         \mapHawkid :: (a -> b) -> (" ++ hawkID++ " a) -> (" ++ hawkID ++ " b)\n\n\ 
                         \substB :: (" ++ hawkID ++ " a) -> (" ++ hawkID ++" a) -> (" ++ hawkID ++ " a)\n\ 
                         \substB x y = B" 
    let file = writeFile "Desktop/hawkID.hs" text 

    return() 

Answer 1

您是否正在輸入文本並按回車鍵以滿足getLine調用？將沒有提示。如果您想要提示，我認爲您需要（例如）putStr，並可能禁用輸出緩衝。

此外，您的通話writeFile將不進行評估 - 你需要把它的do塊就像身體一樣：

import System.IO 

main :: IO() 
main = do 
    hSetBuffering stdout NoBuffering 
    putStr "Hawk ID: " 
    hawkID <- getLine 
    let text = ... 
    writeFile "hawkID.hs" text