I'm trying to write a small web application starting from here: http://adit.io/posts/2013-04-15-making-a-website-with-haskell.html Resolving dependencies... Configuring scotty-0.2.0... Building scotty-0.2.0... Preprocessing library scotty-0.2.0... Web/Scotty.hs:35:8: Could not find module `Control.Monad.Trans.Resource' It is a member of the hidden package `resourcet-0.4.8'. Perhaps you need to add `resourcet' to the build-depends in your .cabal file. Use -v to see a list of the files searched for. Failed to install scotty-0.2.0 My build-depends clause is the following: build-depends: base ==4.5.* , wai ==1.3.* , warp ==1.3.* , http-types ==0.7.* , resourcet , scotty , text , bytestring , blaze-html , persistent , persistent-template , persistent-sqlite , persistent-postgresql , heroku , transformers ==0.3.0.0 , wai-middleware-static ==0.3.2 , wai-extra , time , monad-logger ==0.2.4 Any idea what is wrong with it? I also tried to use the dependencies list without any versions and I get the same error Thanks ovidiu