使用 GHC 7.6.3 编译 thrift 教程的问题

Question

我尝试使用 ghc 7.6.3 将文件 HaskellServer.hs 从 thrift-0.9.0/tutorial/hs 编译为 没用。

在我调用的命令行上

thrift --gen hs tutorial.thrift

thrift --gen hs shared.thrift

没有任何错误。

之后，我尝试编译

ghc HaskellServer.hs

但我得到以下错误输出：

[1 of 7] Compiling Shared_Types     ( Shared_Types.hs, Shared_Types.o ) [flags changed]
[2 of 7] Compiling SharedService_Iface ( SharedService_Iface.hs, SharedService_Iface.o ) [flags
changed]
[3 of 7] Compiling SharedService    ( SharedService.hs, SharedService.o ) [flags changed]
[4 of 7] Compiling Tutorial_Types   ( Tutorial_Types.hs, Tutorial_Types.o ) [flags changed]
[5 of 7] Compiling Calculator_Iface ( Calculator_Iface.hs, Calculator_Iface.o ) [flags changed]
[6 of 7] Compiling Calculator       ( Calculator.hs, Calculator.o ) [flags changed]
[7 of 7] Compiling Main             ( HaskellServer.hs, HaskellServer.o )

HaskellServer.hs:48:33:
    Couldn't match type `GHC.Int.Int32' with `Int'
    Expected type: Maybe Int
      Actual type: Maybe GHC.Int.Int32
    In the first argument of `fromJust', namely `k'
    In the second argument of `(!)', namely `(fromJust k)'
    In the second argument of `($)', namely `(myLog ! (fromJust k))'

HaskellServer.hs:73:60:
    Couldn't match type `Int' with `GHC.Int.Int32'
    Expected type: Maybe GHC.Int.Int32
      Actual type: Maybe Int
    In the `f_InvalidOperation_what' field of a record
    In the second argument of `($)', namely
      `InvalidOperation
         {f_InvalidOperation_what = Just $ fromEnum $ op work,
          f_InvalidOperation_why = Just "Cannot divide by 0"}'
    In the expression:
      throw
      $ InvalidOperation
          {f_InvalidOperation_what = Just $ fromEnum $ op work,
           f_InvalidOperation_why = Just "Cannot divide by 0"}

HaskellServer.hs:74:64:
    Couldn't match expected type `Data.Text.Lazy.Internal.Text'
                with actual type `[Char]'
    In the first argument of `Just', namely `"Cannot divide by 0"'
    In the `f_InvalidOperation_why' field of a record
    In the second argument of `($)', namely
      `InvalidOperation
         {f_InvalidOperation_what = Just $ fromEnum $ op work,
          f_InvalidOperation_why = Just "Cannot divide by 0"}'

HaskellServer.hs:79:53:
    Couldn't match type `[Char]' with `Data.Text.Lazy.Internal.Text'
    Expected type: Data.Text.Lazy.Internal.Text
      Actual type: String
    In the return type of a call of `show'
    In the first argument of `Just', namely `(show val)'
    In the second argument of `SharedStruct', namely
      `(Just (show val))'

HaskellServer.hs:80:52:
    Couldn't match expected type `Int' with actual type `GHC.Int.Int32'
    In the first argument of `M.insert', namely `logid'
    In the second argument of `(.)', namely `(M.insert logid logEntry)'
    In the second argument of `($)', namely
      `return . (M.insert logid logEntry)'

显然，类型有问题，但我不能说这是否是我的具体问题 GHC 版本或 Thrift 本身。

这是第一条错误消息的代码 (HaskellServer.hs:48:33)：

instance SharedService_Iface CalculatorHandler where
  getStruct self k = do
    myLog <- readMVar (mathLog self)
    return $ (myLog ! (fromJust k))

有人可以指出正确的方向吗？

---

更新

生成的 thrift 文件列出了使用的编译标志：

{-# OPTIONS_GHC -fno-warn-name-shadowing #-}
{-# OPTIONS_GHC -fno-warn-unused-imports #-}
{-# OPTIONS_GHC -fno-warn-unused-matches #-}
{-# OPTIONS_GHC -fno-warn-missing-fields #-}
{-# OPTIONS_GHC -fno-warn-missing-signatures #-}

Answer 1

如果不查看更多代码，很难知道您实际使用的是什么类型，但我在这里有一种预感，即 thrift 会生成预期 GHC.Int.Int32 的东西，而您的代码会预期 Int