无法在Haskell平台2012.2.0.0 (Windows XP)上cabal-install acid-state

Question

使用cabal，我尝试在Haskell Platform 2012.2.0.0 (Windows XP)上安装acid-state，但得到以下错误：

src-win32\FileIO.hs:43:5:
    Not in scope: catchIO Perhaps you meant `catch' (imported from Prelude)

src-win32\FileIO.hs:55:6:
    Not in scope: tryE Perhaps you meant `try' (imported from Control.Exception.Extensible)

src-win32\FileIO.hs:56:6:
    Not in scope: tryE
    Perhaps you meant `try' (imported from Control.Exception.Extensible)
cabal: Error: some packages failed to install:
acid-state-0.8.1 failed during the building phase. The exception was:
ExitFailure 1

Answer 1

在使用可扩展异常系统时，这类问题经常出现。tryE和catchIO是标准样板；它们只是将catch和try专门化以使用SomeException和IOException

 import Control.Exception.Extensible(try,throw)
 import Control.Exception(SomeException,IOException)
 import qualified Control.Exception as E 
 tryE :: IO a -> IO (Either SomeException a)
 tryE = try
 catchIO :: IO a -> (IOException -> IO a) -> IO a
 catchIO = E.catch

执行cabal unpack acid-state操作，并将src-win32/FileIO.hs替换为this，后者在18ff https://gist.github.com/4032603行上定义它们，然后从外部目录(包含acid-state.cabal文件的那个目录)执行cabal install。

可能有一些额外的错误，因为我现在不能测试它。正如Paul R.所说，当你编译它的时候，把它发送给维护者。包的维护很繁重，但看起来他们需要一名Windows测试员。酸状态当然是值得麻烦的。您还应该尝试examples/目录中的一些模块，它们在任何情况下都是一个很好的教程。如果你有更多的麻烦回信，我们可以一起设计一个合适的补丁文件。