Question

每当我尝试使用newtypes编译haskell程序时，我会收到一条错误，指出“因使用......而导致 blah blah 没有实例”，例如：

No instance for (Hashable NT.EndPointAddress)
  arising from a use of `hashable-1.2.0.10:Data.Hashable.Class.$gdmhashWithSalt'
Possible fix:
  add an instance declaration for (Hashable NT.EndPointAddress)
In the expression:
  (hashable-1.2.0.10:Data.Hashable.Class.$gdmhashWithSalt)
In an equation for `hashWithSalt':
    hashWithSalt
      = (hashable-1.2.0.10:Data.Hashable.Class.$gdmhashWithSalt)
In the instance declaration for `Hashable NodeId'

任何人都可以建议可能发生的事情吗？

谢谢，

卡尔

我添加了与上述错误消息相关的代码。它发布在下面。错误发生在第132行。代码来自Types.hs，它来自github上发布的distributed-process的开发分支。对于我尝试编译其中包含newtypes的任何代码，我收到同样的错误。

{-# LANGUAGE DeriveGeneric #-}

-- | Types used throughout the Cloud Haskell framework
--
-- We collect all types used internally in a single module because
-- many of these data types are mutually recursive and cannot be split across
-- modules.
module Control.Distributed.Process.Internal.Types
  ( -- * Node and process identifiers
    NodeId(..)
  , LocalProcessId(..)
  , ProcessId(..)
  , Identifier(..)
  , nodeOf
  , firstNonReservedProcessId
  , nullProcessId
    -- * Local nodes and processes
  , LocalNode(..)
  , Tracer(..)
  , LocalNodeState(..)
  , LocalProcess(..)
  , LocalProcessState(..)
  , Process(..)
  , runLocalProcess
  , ImplicitReconnect(..)
    -- * Typed channels
  , LocalSendPortId
  , SendPortId(..)
  , TypedChannel(..)
  , SendPort(..)
  , ReceivePort(..)
    -- * Messages
  , Message(..)
  , isEncoded
  , createMessage
  , createUnencodedMessage
  , unsafeCreateUnencodedMessage
  , messageToPayload
  , payloadToMessage
    -- * Node controller user-visible data types
  , MonitorRef(..)
  , ProcessMonitorNotification(..)
  , NodeMonitorNotification(..)
  , PortMonitorNotification(..)
  , ProcessExitException(..)
  , ProcessLinkException(..)
  , NodeLinkException(..)
  , PortLinkException(..)
  , ProcessRegistrationException(..)
  , DiedReason(..)
  , DidUnmonitor(..)
  , DidUnlinkProcess(..)
  , DidUnlinkNode(..)
  , DidUnlinkPort(..)
  , SpawnRef(..)
  , DidSpawn(..)
  , WhereIsReply(..)
  , RegisterReply(..)
  , ProcessInfo(..)
  , ProcessInfoNone(..)
    -- * Node controller internal data types
  , NCMsg(..)
  , ProcessSignal(..)
    -- * Accessors
  , localProcesses
  , localPidCounter
  , localPidUnique
  , localConnections
  , localProcessWithId
  , localConnectionBetween
  , monitorCounter
  , spawnCounter
  , channelCounter
  , typedChannels
  , typedChannelWithId
    -- * Utilities
  , forever'
  ) where

import System.Mem.Weak (Weak)
import Data.Map (Map)
import Data.Int (Int32)
import Data.Typeable (Typeable, typeOf)
import Data.Binary (Binary(put, get), putWord8, getWord8, encode)
import qualified Data.ByteString as BSS (ByteString, concat, copy)
import qualified Data.ByteString.Lazy as BSL
  ( ByteString
  , toChunks
  , splitAt
  , fromChunks
  , length
  )
import qualified Data.ByteString.Lazy.Internal as BSL (ByteString(..))
import Data.Accessor (Accessor, accessor)
import Control.Category ((>>>))
import Control.DeepSeq (NFData(..))
import Control.Exception (Exception)
import Control.Concurrent (ThreadId)
import Control.Concurrent.Chan (Chan)
import Control.Concurrent.STM (STM)
import qualified Network.Transport as NT (EndPoint, EndPointAddress, Connection)
import Control.Applicative (Applicative, Alternative, (<$>), (<*>))
import Control.Monad.Reader (MonadReader(..), ReaderT, runReaderT)
import Control.Monad.IO.Class (MonadIO)
import Control.Distributed.Process.Serializable
  ( Fingerprint
  , Serializable
  , fingerprint
  , encodeFingerprint
  , sizeOfFingerprint
  , decodeFingerprint
  , showFingerprint
  )
import Control.Distributed.Process.Internal.CQueue (CQueue)
import Control.Distributed.Process.Internal.StrictMVar (StrictMVar)
import Control.Distributed.Process.Internal.WeakTQueue (TQueue)
import Control.Distributed.Static (RemoteTable, Closure)
import qualified Control.Distributed.Process.Internal.StrictContainerAccessors as DAC (mapMaybe)

import Data.Hashable
import GHC.Generics

--------------------------------------------------------------------------------
-- Node and process identifiers                                               --
--------------------------------------------------------------------------------

-- | Node identifier
newtype NodeId = NodeId { nodeAddress :: NT.EndPointAddress }
  deriving (Eq, Ord, Typeable, Generic)
instance Binary NodeId where
instance NFData NodeId
instance Hashable NodeId where
instance Show NodeId where
  show (NodeId addr) = "nid://" ++ show addr

-- | A local process ID consists of a seed which distinguishes processes from
-- different instances of the same local node and a counter
data LocalProcessId = LocalProcessId
  { lpidUnique  :: {-# UNPACK #-} !Int32
  , lpidCounter :: {-# UNPACK #-} !Int32
  }
  deriving (Eq, Ord, Typeable, Generic, Show)

Answer 1

好的，明白了。 EndPointAddress在hashable的主分支中没有实例。我必须下载以下包的开发分支才能成功编译distributed-process-platform：

hashable
distributed-process
distributed-process-static
rank1dynamic
network-transport
network-transport-tcp
distributed-process-simplelocalnet
distributed-process-platform

我在以下帖子compiling distributed-process

中找到了此信息

感谢您花时间回答我的帖子！

Answer 2

您似乎安装了多个版本的hashable。使用ghc-pkg list，ghc-pkg unregister等来确定正在发生的事情并进行修复。几乎可以肯定，您只想拥有hashable的一个版本。

试图编译包含newtypes的任何haskell程序

2 个答案: