我正在尝试更新ubuntu 14.04上的pandoc但由于未解析的依赖项而失败：
leonardo@ICI-LAS:~$ sudo cabal update
Downloading the latest package list from hackage.haskell.org
ICI-LAS:~$ sudo cabal install pandoc pandoc-citeproc
Resolving dependencies...
cabal: Could not resolve dependencies:
trying: pandoc-1.15.2.1
trying: pandoc-1.15.2.1:-old-locale
trying: pandoc-1.15.2.1:+network-uri
trying: network-2.6.0.2/installed-f92...
rejecting: unix-2.6.0.1/installed-808... (conflict: unix =>
time==1.4.0.1/installed-11d..., pandoc-1.15.2.1:old-locale => time>=1.5 &&
<1.6)
rejecting: unix-2.7.1.0, 2.7.0.1, 2.7.0.0, 2.6.0.1, 2.6.0.0, 2.5.1.1, 2.5.1.0,
2.5.0.0, 2.4.2.0, 2.4.1.0, 2.4.0.2, 2.4.0.1, 2.4.0.0, 2.3.2.0, 2.3.1.0,
2.3.0.0, 2.2.0.0, 2.0 (conflict: network => unix==2.6.0.1/installed-808...)
ICI-LAS:~$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.6.3
ICI-LAS:~$ cabal --version
cabal-install version 1.16.0.2
using version 1.16.0 of the Cabal library
如何解决此问题？