Can cabal not un-install packages?

Question

cabal help shows thers isnot "uninstall" option.

then what's the best way to uninstall the packages installed by cabal ?

% cabal update
% cabal install mighttpd2

mighttpd2 is installed successfully. However the ghc-pkg cannot find & unregister it:

% ghc-pkg list | grep -i might
% ghc-pkg unregister mighttpd2
ghc-pkg: cannot find package mighttpd2

Sincerely!

>find .cabal | grep -i mighttp
.cabal/share/doc/mighttpd2-2.3.3
.cabal/share/doc/mighttpd2-2.3.3/LICENSE
.cabal/share/mighttpd2-2.3.3
.cabal/share/mighttpd2-2.3.3/sample.conf
.cabal/share/mighttpd2-2.3.3/sample.route
.cabal/packages/hackage.haskell.org/mighttpd2
.cabal/packages/hackage.haskell.org/mighttpd2/2.3.3
.cabal/packages/hackage.haskell.org/mighttpd2/2.3.3/mighttpd2-2.3.3.tar.gz

>ghc-pkg list | grep -i package\.conf
 /usr/local/lib/ghc-7.0.3/package.conf.d:
 /home/sw2wolf/.ghc/i386-freebsd-7.0.3/package.conf.d:

So ".cabal/packages/hackage.haskell.org" cannot be seen by ghc-pkg.

You can't 'uninstall', you can only unregister it: haskell.org/haskellwiki/… — wkl
My guess is a user mis-match; does cabal list mightppd2 say it's installed? Are you sure you're using the same user (i.e. sw2wolf) to install the package as doing the ghc-pkg stuff? — ivanm
I am sure it is the same user. 1cabal list mightppd2 reports "No matches found." — z_axis

gatoatigrado gatoatigrado · Accepted Answer · 2011-08-31T04:47:06

you might not have the Cabal path as part of your GHC path.

step 1

First, try to find out what your GHC package path is,

ghc-pkg list
    # displays stuff like "/home/username/.../package.conf.d"

then, make sure the one Cabal is writing to is active. For me, Cabal adds packages to

/home/username/.ghc/x86_64-linux-7.0.4/package.conf.d

step 2

If there is no such directory on your system, see what Cabal's writing.

strace -f -o trace.txt cabal install mighttpd2
grep "package\.cache" trace.txt

then add the package path to this system environment variable

export GHC_PACKAGE_PATH=NEWPATH:/usr/local/lib/ghc-7.0.3/package.conf.d

try again, if it doesn't work proceed to step 3

step 3

look in that directory and see if there's a file like

mighthttpd2-version-LONGHASHCODE.conf

if it's there, then you probably need to recache

ghc-pkg recache --user

Can cabal not un-install packages?

2 Answers

step 1

step 2

step 3