我在Eclipse上安装了EclipseFP，当它启动时提到我需要安装buildwrapper和scion-browser。我更新了cabal并尝试安装每个，但我从sudo cabal install buildwrapper收到此错误：
david@mycomputer:~$ sudo cabal install buildwrapper
Resolving dependencies...
cabal: internal error: could not construct a valid install plan.
The proposed (invalid) plan contained the following problems:
The following packages are involved in a dependency cycle buildwrapper-0.5.2
我从sudo cabal install scion-browser收到此消息说我需要指定不同的基本库（相关问题：我如何告诉cabal使用不同的基本库？）
david@mycomputer:~$ sudo cabal install scion-browser
Resolving dependencies...
cabal: cannot configure conduit-0.4.2. It requires base >=4.3 && <5
For the dependency on base >=4.3 && <5 there are these packages: base-4.3.0.0,
base-4.3.1.0, base-4.4.0.0, base-4.4.1.0, base-4.5.0.0 and base-4.5.1.0.
However none of them are available.
base-4.3.0.0 was excluded because unix-2.4.0.0 requires base ==4.2.0.0
base-4.3.0.0 was excluded because template-haskell-2.4.0.0 requires base
==4.2.0.0
base-4.3.0.0 was excluded because process-1.0.1.2 requires base ==4.2.0.0
base-4.3.0.0 was excluded because pretty-1.0.1.1 requires base ==4.2.0.0
base-4.3.0.0 was excluded because old-time-1.0.0.3 requires base ==4.2.0.0
base-4.3.0.0 was excluded because old-locale-1.0.0.2 requires base ==4.2.0.0
base-4.3.0.0 was excluded because hpc-0.5.0.4 requires base ==4.2.0.0
base-4.3.0.0 was excluded because ghc-binary-0.5.0.2 requires base ==4.2.0.0
base-4.3.0.0 was excluded because filepath-1.1.0.3 requires base ==4.2.0.0
base-4.3.0.0 was excluded because directory-1.0.1.0 requires base ==4.2.0.0
base-4.3.0.0 was excluded because containers-0.3.0.0 requires base ==4.2.0.0
base-4.3.0.0 was excluded because bytestring-0.9.1.5 requires base ==4.2.0.0
base-4.3.0.0 was excluded because bin-package-db-0.0.0.0 requires base
==4.2.0.0
base-4.3.0.0 was excluded because array-0.3.0.0 requires base ==4.2.0.0
base-4.3.0.0 was excluded because Cabal-1.8.0.2 requires base ==4.2.0.0
base-4.3.0.0 was excluded because ghc-6.12.1 requires base ==4.2.0.0
base-4.3.0.0 was excluded because of the top level dependency base -any
base-4.3.1.0 was excluded because unix-2.4.0.0 requires base ==4.2.0.0
base-4.3.1.0 was excluded because template-haskell-2.4.0.0 requires base
==4.2.0.0
base-4.3.1.0 was excluded because process-1.0.1.2 requires base ==4.2.0.0
base-4.3.1.0 was excluded because pretty-1.0.1.1 requires base ==4.2.0.0
base-4.3.1.0 was excluded because old-time-1.0.0.3 requires base ==4.2.0.0
base-4.3.1.0 was excluded because old-locale-1.0.0.2 requires base ==4.2.0.0
base-4.3.1.0 was excluded because hpc-0.5.0.4 requires base ==4.2.0.0
base-4.3.1.0 was excluded because ghc-binary-0.5.0.2 requires base ==4.2.0.0
base-4.3.1.0 was excluded because filepath-1.1.0.3 requires base ==4.2.0.0
base-4.3.1.0 was excluded because directory-1.0.1.0 requires base ==4.2.0.0
base-4.3.1.0 was excluded because containers-0.3.0.0 requires base ==4.2.0.0
base-4.3.1.0 was excluded because bytestring-0.9.1.5 requires base ==4.2.0.0
base-4.3.1.0 was excluded because bin-package-db-0.0.0.0 requires base
==4.2.0.0
base-4.3.1.0 was excluded because array-0.3.0.0 requires base ==4.2.0.0
base-4.3.1.0 was excluded because Cabal-1.8.0.2 requires base ==4.2.0.0
base-4.3.1.0 was excluded because ghc-6.12.1 requires base ==4.2.0.0
base-4.3.1.0 was excluded because of the top level dependency base -any
base-4.4.0.0 was excluded because uniplate-1.6.7 requires base >=4 && <4.4
base-4.4.0.0 was excluded because unix-2.4.0.0 requires base ==4.2.0.0
base-4.4.0.0 was excluded because template-haskell-2.4.0.0 requires base
==4.2.0.0
base-4.4.0.0 was excluded because process-1.0.1.2 requires base ==4.2.0.0
base-4.4.0.0 was excluded because pretty-1.0.1.1 requires base ==4.2.0.0
base-4.4.0.0 was excluded because old-time-1.0.0.3 requires base ==4.2.0.0
base-4.4.0.0 was excluded because old-locale-1.0.0.2 requires base ==4.2.0.0
base-4.4.0.0 was excluded because hpc-0.5.0.4 requires base ==4.2.0.0
base-4.4.0.0 was excluded because ghc-binary-0.5.0.2 requires base ==4.2.0.0
base-4.4.0.0 was excluded because filepath-1.1.0.3 requires base ==4.2.0.0
base-4.4.0.0 was excluded because directory-1.0.1.0 requires base ==4.2.0.0
base-4.4.0.0 was excluded because containers-0.3.0.0 requires base ==4.2.0.0
base-4.4.0.0 was excluded because bytestring-0.9.1.5 requires base ==4.2.0.0
base-4.4.0.0 was excluded because bin-package-db-0.0.0.0 requires base
==4.2.0.0
base-4.4.0.0 was excluded because array-0.3.0.0 requires base ==4.2.0.0
base-4.4.0.0 was excluded because Cabal-1.8.0.2 requires base ==4.2.0.0
base-4.4.0.0 was excluded because ghc-6.12.1 requires base ==4.2.0.0
base-4.4.0.0 was excluded because of the top level dependency base -any
base-4.4.1.0 was excluded because uniplate-1.6.7 requires base >=4 && <4.4
base-4.4.1.0 was excluded because unix-2.4.0.0 requires base ==4.2.0.0
base-4.4.1.0 was excluded because template-haskell-2.4.0.0 requires base
==4.2.0.0
base-4.4.1.0 was excluded because process-1.0.1.2 requires base ==4.2.0.0
base-4.4.1.0 was excluded because pretty-1.0.1.1 requires base ==4.2.0.0
base-4.4.1.0 was excluded because old-time-1.0.0.3 requires base ==4.2.0.0
base-4.4.1.0 was excluded because old-locale-1.0.0.2 requires base ==4.2.0.0
base-4.4.1.0 was excluded because hpc-0.5.0.4 requires base ==4.2.0.0
base-4.4.1.0 was excluded because ghc-binary-0.5.0.2 requires base ==4.2.0.0
base-4.4.1.0 was excluded because filepath-1.1.0.3 requires base ==4.2.0.0
base-4.4.1.0 was excluded because directory-1.0.1.0 requires base ==4.2.0.0
base-4.4.1.0 was excluded because containers-0.3.0.0 requires base ==4.2.0.0
base-4.4.1.0 was excluded because bytestring-0.9.1.5 requires base ==4.2.0.0
base-4.4.1.0 was excluded because bin-package-db-0.0.0.0 requires base
==4.2.0.0
base-4.4.1.0 was excluded because array-0.3.0.0 requires base ==4.2.0.0
base-4.4.1.0 was excluded because Cabal-1.8.0.2 requires base ==4.2.0.0
base-4.4.1.0 was excluded because ghc-6.12.1 requires base ==4.2.0.0
base-4.4.1.0 was excluded because of the top level dependency base -any
base-4.5.0.0 was excluded because uniplate-1.6.7 requires base >=4 && <4.4
base-4.5.0.0 was excluded because unix-2.4.0.0 requires base ==4.2.0.0
base-4.5.0.0 was excluded because template-haskell-2.4.0.0 requires base
==4.2.0.0
base-4.5.0.0 was excluded because process-1.0.1.2 requires base ==4.2.0.0
base-4.5.0.0 was excluded because pretty-1.0.1.1 requires base ==4.2.0.0
base-4.5.0.0 was excluded because old-time-1.0.0.3 requires base ==4.2.0.0
base-4.5.0.0 was excluded because old-locale-1.0.0.2 requires base ==4.2.0.0
base-4.5.0.0 was excluded because hpc-0.5.0.4 requires base ==4.2.0.0
base-4.5.0.0 was excluded because ghc-binary-0.5.0.2 requires base ==4.2.0.0
base-4.5.0.0 was excluded because filepath-1.1.0.3 requires base ==4.2.0.0
base-4.5.0.0 was excluded because directory-1.0.1.0 requires base ==4.2.0.0
base-4.5.0.0 was excluded because containers-0.3.0.0 requires base ==4.2.0.0
base-4.5.0.0 was excluded because bytestring-0.9.1.5 requires base ==4.2.0.0
base-4.5.0.0 was excluded because bin-package-db-0.0.0.0 requires base
==4.2.0.0
base-4.5.0.0 was excluded because array-0.3.0.0 requires base ==4.2.0.0
base-4.5.0.0 was excluded because Cabal-1.8.0.2 requires base ==4.2.0.0
base-4.5.0.0 was excluded because ghc-6.12.1 requires base ==4.2.0.0
base-4.5.0.0 was excluded because of the top level dependency base -any
base-4.5.1.0 was excluded because uniplate-1.6.7 requires base >=4 && <4.4
base-4.5.1.0 was excluded because unix-2.4.0.0 requires base ==4.2.0.0
base-4.5.1.0 was excluded because template-haskell-2.4.0.0 requires base
==4.2.0.0
base-4.5.1.0 was excluded because process-1.0.1.2 requires base ==4.2.0.0
base-4.5.1.0 was excluded because pretty-1.0.1.1 requires base ==4.2.0.0
base-4.5.1.0 was excluded because old-time-1.0.0.3 requires base ==4.2.0.0
base-4.5.1.0 was excluded because old-locale-1.0.0.2 requires base ==4.2.0.0
base-4.5.1.0 was excluded because hpc-0.5.0.4 requires base ==4.2.0.0
base-4.5.1.0 was excluded because ghc-binary-0.5.0.2 requires base ==4.2.0.0
base-4.5.1.0 was excluded because filepath-1.1.0.3 requires base ==4.2.0.0
base-4.5.1.0 was excluded because directory-1.0.1.0 requires base ==4.2.0.0
base-4.5.1.0 was excluded because containers-0.3.0.0 requires base ==4.2.0.0
base-4.5.1.0 was excluded because bytestring-0.9.1.5 requires base ==4.2.0.0
base-4.5.1.0 was excluded because bin-package-db-0.0.0.0 requires base
==4.2.0.0
base-4.5.1.0 was excluded because array-0.3.0.0 requires base ==4.2.0.0
base-4.5.1.0 was excluded because Cabal-1.8.0.2 requires base ==4.2.0.0
base-4.5.1.0 was excluded because ghc-6.12.1 requires base ==4.2.0.0
base-4.5.1.0 was excluded because of the top level dependency base -any
有谁知道如何安装这些库以便我可以使用EclipseFP？在Eclipse启动的弹出窗口中，它有一个安装这些库，但按下它不会做任何事情。
答案 0 :(得分：1)
您可以通过升级GHC获得更新的基础。我推荐这个：GHC 6.12现在已经有2.5年了，那时候发生了很多事情。
猜测，循环依赖来自使用旧版本的cabal（-install）。较新版本的cabal允许单个包提供库和可执行文件（可能依赖于库）;对于旧版本，这可能看起来像单包循环依赖。