HappStack中的Haskell Monads msum
|
从
http://happstack.com/docs/crashcourse/HappstackState.html
当我运行服务器时，窥视计数器增加了
1当我偷看
2当我不偷看
有问题的相关代码是：
handlers :: ServerPart Response
handlers =
msum [ dir \"peek\" $ do c <- query PeekCounter
ok $ toResponse $ \"peeked at the count and saw: \" ++ show (unCounter c)
, do c <- update (AddCounter 1)
ok $ toResponse $ \"New count is: \" ++ show (unCounter c)
]
handlers :: ServerPart Response
handlers =
msum [ dir \"peek\" $ do c <- query PeekCounter
ok $ toResponse $ \"peeked at the count and saw: \" ++ show (unCounter c)
, do ok $ toResponse $ \"Stop here.\"
, do c <- update (AddCounter 1)
ok $ toResponse $ \"New count is: \" ++ show (unCounter c)
]
没有找到相关结果
已邀请:
1 个回复
布埃郝卞簿
handlers :: ServerPart Response handlers = msum [ dir \"peek\" $ do c <- query PeekCounter ok $ toResponse $ \"peeked at the count and saw: \" ++ show (unCounter c) , do nullDir c <- update (AddCounter 1) ok $ toResponse $ \"New count is: \" ++ show (unCounter c) ]handlers :: ServerPart Response handlers = msum [ dir \"peek\" $ do c <- query PeekCounter ok $ toResponse $ \"peeked at the count and saw: \" ++ show (unCounter c) , dir \"favicon.ico\" $ notFound (toResponse \"sorry, no favicon.ico\") , do c <- update (AddCounter 1) ok $ toResponse $ \"New count is: \" ++ show (unCounter c) ]