RequestBody应用于太多类型的参数

Question

什么没有以下函数打字：

import qualified Control.Exception as E
import Data.Conduit (ResourceT)
import Network.HTTP.Types (Method, Status(..))
import Network.HTTP.Conduit
import qualified Data.ByteString.Lazy.Char8 as LBS
doHttps :: Method -> String
        -> Maybe (RequestBody (ResourceT IO))
        -> IO (Either E.SomeException (Response LBS.ByteString))
doHttps reqMethod url body = undefined

它产生以下错误：

RequestBody is applied to too many type arguments
    In the type signature for `doHttps':
      doHttps :: Method
                 -> String
                    -> Maybe (RequestBody (ResourceT IO))
                       -> IO (Either E.SomeException (Response LBS.ByteString))
Failed, modules loaded: none.

doHttps函数是此功能的简化版本。但是显然，模块中的原始功能Typechecks中的原始功能，但上述片段不起作用。为什么会发生？

Answer 1

http-condit库的不同版本。在版本1中。

http://hackage.haskell.org/package/http-conduit-1.9.6/docs/network-http-conduit.html#t:requequest

但是，在版本2中。*，它不采用类型参数：

http://hackage.haskell.org/package/http-conduit-2.0.0.0.0/docs/network-http-conduit.html#tml#t:requequest