mark@server:~$ sudo cabal install pandoc pandoc-citeproc

mark@server:~$ pandoc -v
pandoc 1.12.2.1

All the requested packages are already installed:
pandoc-1.13.2
pandoc-citeproc-0.6
Use --reinstall if you want to reinstall anyway.

PATH=$HOME/.cabal/bin:$PATH
export PATH

pandoc --version