Dear list Like many other I seem to be struggling with some of the concepts of cabal and cabal-install. For the records: I use cabal-install 1.20.0.3 and ghc 7.8.3 on arch linux. For starters, I implemented my own idea of an improved prelude, called the package efa-prelude and the module it exports Efa.Prelude. I then built the package and installed it using `cabal install --user`. This worked and a folder for the library was created at "$HOME/.cabal/lib/x86_64-linux-ghc-7.8.3/efa-prelude-0.1.0". I also registered the library using `cabal register --user` and now cabal prints some information about the package when I type `cabal info efa-prelude`. I am also able to import Efa.Prelude into ghci. However, when I now try to use this library in another local project using a sandbox this time, I can build the project but when I try to install it into the sandbox I get the following error message: Resolving dependencies... cabal: Could not resolve dependencies: trying: test-0.1.0 (user goal) next goal: efa-prelude (dependency of test-0.1.0) Dependency tree exhaustively searched. I just tried and the install works if I do it outside of a sandbox. Obviously I am missing something crucial here. Could somebody please point me in the right direction what is needed to make my own packages available in a sanboxed install? Thanks for your time Stefan