What's wrong? How can i install and use library in haskell?
First thing is to do 'ghc-pkg list'. If your package doesn't show up then it's not installed, according to the package registry. 'cabal install' should have registered it. If it is in the list, then it depends how you're building. If you use ghc manually, then you have to give '-package xyz'. If you use 'ghc --make', ghc will automatically add the -package for you. If you use cabal, you put the package in the dependencies, and 'cabal build' will add -package for you. If the package has parens, then someone hid it, and you'll have to do 'ghc-pkg expose' on it. If you're doing everything else right and it still doesn't find the package, then you can run ghc -v and it'll print lots of details. It might have something about 'hiding xyz because of <some version thing>', which means you're depending on libraries that expect different versions of the underlying library. You can sometimes get out of this by carefully upgrading or downgrading certain libraries.