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我读了真实世界哈斯克尔第9章 有一种maybeIO函数封装了IO功能结果变成可能:如何使用haskell控件。异常处理返回一个IO(也许)
maybeIO :: IO a -> IO (Maybe a)
maybeIO act = handle(\_ -> return Nothing) (liftM Just act)
但是这个代码不会工作在GHC 7 +,我不知道如何修改这个代码,以便它会GHC 7工作,我试图
import Control.Exception (bracket, handle, SomeException(..))
maybeIO :: IO a -> IO (Maybe a)
maybeIO act = handle(\(SomeException e) -> return Nothing) (liftM Just act)
,但我得到一个解析错误:在顶级
是的,它的工作原理,谢谢。必须将其他代码混淆编译器。 – 2012-02-14 19:22:06