看起来大部分版本都在工作，但实际安装失败了。
小心地放置echo命令显示该命令是失败的命令：
install_pkg "cabal-install"
这是我收到的错误：
cleaning...
Linking Setup ...
Configuring cabal-install-1.17.0...
Building cabal-install-1.17.0...
Preprocessing library cabal-install-1.17.0...
[ 1 of 71] Compiling Distribution.Compat.FilePerms ( Distribution/Compat/FilePerms.hs, dist/build/Distribution/Compat/FilePerms.o )
[ 2 of 71] Compiling Distribution.Compat.Semaphore ( Distribution/Compat/Semaphore.hs, dist/build/Distribution/Compat/Semaphore.o )
Distribution/Compat/Semaphore.hs:12:26:
Module `Control.Exception' does not export `mask_'
Error during cabal-install bootstrap:
Building the cabal-install package failed
以下是完整的成绩单：
Checking installed packages for ghc-6.12.3...
Cabal is already installed and the version is ok.
transformers is already installed and the version is ok.
mtl is already installed and the version is ok.
deepseq is already installed and the version is ok.
text is already installed and the version is ok.
parsec is already installed and the version is ok.
network is already installed and the version is ok.
time is already installed and the version is ok.
HTTP is already installed and the version is ok.
zlib is already installed and the version is ok.
random is already installed and the version is ok.
stm is already installed and the version is ok.
===========================================
cleaning...
Linking Setup ...
Configuring cabal-install-1.17.0...
Building cabal-install-1.17.0...
Preprocessing library cabal-install-1.17.0...
[ 1 of 71] Compiling Distribution.Compat.FilePerms ( Distribution/Compat/FilePerms.hs, dist/build/Distribution/Compat/FilePerms.o )
[ 2 of 71] Compiling Distribution.Compat.Semaphore ( Distribution/Compat/Semaphore.hs, dist/build/Distribution/Compat/Semaphore.o )
Distribution/Compat/Semaphore.hs:12:26:
Module `Control.Exception' does not export `mask_'
Error during cabal-install bootstrap:
Building the cabal-install package failed