Haskell检查程序avaliablity

Question

是否可以检查给定的字符串是否代表$ PATH(%path%)中的可执行文件？它必须可移植到Windows.只是调用它并查看返回状态的想法不适用,因为非零可能意味着程序错误或程序未找到.好吧,在代码中,我想要关注

possibleCompilers = ["gcc", "icc", "foo", "bar.exe"]
presentCompiler :: IO String

Answer 1

这项任务应该可以使用System.Directory.findExecutable.

possibleCompiler :: IO (Maybe String)
possibleCompiler = check possibleCompilers
  where
    check [] = return Nothing
    check (c:cs) = do
       mbc <- findExecutable c
       case mbc of
         Just _ -> return mbc
         Nothing -> check cs

我改变了类型IO (Maybe String),因为可能没有找到任何候选人.