yesod安装失败

Question

我通常发现有超过一半的大型软件包的安装失败，这对新用户来说是一个致命的缺陷！

这次我正在尝试安装yesod，有什么提示吗？

> cabal install yesod
  ...
Loading package time-1.2.0.5 ...

GHCi runtime linker: fatal error: I found a duplicate definition for symbol
   _get_current_timezone_seconds
whilst processing object file
   C:\Users\guthrie\AppData\Roaming\cabal\time-1.2.0.5\ghc-7.4.1\HStime-1.2.0.5.o
This could be caused by:
   * Loading two different object files which export the same symbol
   * Specifying the same object file twice on the GHCi command line
   * An incorrect `package.conf' entry, causing some object to be
     loaded twice.
GHCi cannot safely continue in this situation.  Exiting now.  Sorry.

cabal: Error: some packages failed to install:
authenticate-1.3.1.1 depends on http-conduit-1.6.1.1 which failed to install.
http-conduit-1.6.1.1 failed during the building phase. The exception was:
ExitFailure 1
yesod-1.1.1.2 depends on yesod-core-1.1.2.1 which failed to install.
yesod-auth-1.1.1.1 depends on yesod-core-1.1.2.1 which failed to install.
yesod-core-1.1.2.1 failed during the building phase. The exception was:
ExitFailure 1
yesod-form-1.1.3 depends on yesod-core-1.1.2.1 which failed to install.
yesod-json-1.1.0 depends on yesod-core-1.1.2.1 which failed to install.
yesod-persistent-1.1.0 depends on yesod-core-1.1.2.1 which failed to install.

Answer 1

yesod使用与Haskell平台不同的alex包版本。除了ghc之外，我总是从发行版的包管理器安装alex和happy，然后使用cabal。或者，您可以始终使用

cabal update && cabal install alex happy
cabal install yesod-platform

Answer 2

这很可能是由于尝试同时安装两个版本的时间包造成的。您是否可以尝试运行cabal install yesod-platform并查看问题是否仍然存在？

正如@Inaimathi所说，这可能是由于旧版本的cabal造成的。也许也可以试试cabal update && cabal install cabal-install。