Cabal不安装4.7.0.0版本的基础版

Question

我需要Data.E v.4.7.0.0的新函数"isLeft",但cabal不会安装新库.

Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Users\Alberto>cabal update
Downloading the latest package list from hackage.haskell.org
Note: there is a new version of cabal-install available.
To upgrade, run: cabal install cabal-install

C:\Users\Alberto>cabal install base
Resolving dependencies...
All the requested packages are already installed:
base-4.6.0.1
Use --reinstall if you want to reinstall anyway.

C:\Users\Alberto>date
The current date is: 19/04/2014

为什么会这样？

如何将基础软件包升级到4.7版？

Answer 1

base是一个特殊的包.你不能升级它.如果你想要base-4.7,你将不得不使用GHC 7.8.