On my CentOS 7 I have installed cabal-install thus:

yum install cabal-install

This was successful.

When I try to use it to install something it reports (not unexpectedly):-

You may need to run 'cabal update' to get the latest list of available packages.

So I try to do this.

cabal update

This takes hours, but does finally complete. At the end it reports:-

Note: there is a new version of cabal-install available.
To upgrade, run: cabal install cabal-install

So I try to do exactly that, to which it reports:-

Resolving dependencies...
cabal: internal error when reading packing index: failed to parse .cabal
fileThe package index or index cache is probably corrupt. Running cabal update
might fix it.

Surely cabal update is what literally just created it?

Anyway, I tried it again, left it for hours to finish, it said:-

Downloading the latest package list from hackage.haskell.org

and then everything was just the same as before. It hadn’t fixed anything.

What does one do to diagnose and fix this? All I want is to install shelltestrunner!