Can cabal not un-install packages?

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 | g开发者_Go百科rep -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 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

The GHC package system is not used for executables, and the mighttpd2 package only builds executables. To uninstall it, simply remove the two executables (mighty and mkindex) and the two data files (sample.conf and sample.route) listed in the package's cabal file. You can find which directories these files were installed to by perusing cabal's config file in ~/.cabal/config.