install_cabal.sh

cabal_version=1.20.0.3
cabal_directory=Cabal-${cabal_version}
cabal_archive=${cabal_directory}.tar.gz

curl -O https://www.haskell.org/cabal/release/cabal-${cabal_version}/${cabal_archive}
tar xvzf ${cabal_archive}
cd ${cabal_directory}
ghc --make Setup
./Setup configure --prefix /opt/local
mkdir tmp
TMPDIR=tmp ./Setup build
./Setup install
rm -fr tmp

cabal_install_version=1.20.0.6
cabal_install_directory=cabal-install-${cabal_install_version}
cabal_install_archive=${cabal_install_directory}.tar.gz

curl -O https://www.haskell.org/cabal/release/${cabal_install_directory}/${cabal_install_archive}
tar xvzf ${cabal_install_archive}
cd ${cabal_install_directory}
ghc --make Setup
./Setup configure --prefix /opt/local
mkdir tmp
TMPDIR=tmp ./Setup build
./Setup install
rm -fr tmp

Breaks at:

[72 of 78] Compiling Distribution.Simple.Configure ( Distribution/Simple/Configure.hs, dist/build/Distribution/Simple/Configure.o )
ghc: internal error: getMBlock: mmap: Resource temporarily unavailable
    (GHC version 7.6.3 for x86_64_unknown_solaris2)
    Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

I suppose you already found out, but that's an out of memory error.