I use Ubuntu 14.04. Outside of a stack context, I have been using GHC 7.8.4. I tried to install 7.10.3. ./configure worked, but make install failed with this error: make[1]: *** No rule to make target `utils/haddock/dist/build/tmp/haddock', needed by `install_libexecs'. Stop. make: *** [install] Error 2 I tried to manually undo the install, by deleting it from /usr/local/lib, and by changing all the symlinks in /usr/local/bin back to 7.8.4. If I run ghci without stack, it works, and is still at version 7.8.4. But now cabal and stack are producing errors. "cabal update" runs, but "cabal install" gets confused: jeff@jeffLenovUbu:~/dwt_git_hask$ cabal install regex-compat Warning: cannot determine version of /usr/local/bin/hpc : "" Warning: cannot determine version of /usr/local/bin/hsc2hs : "" Resolving dependencies... Configuring regex-posix-0.95.2... Building regex-posix-0.95.2... Preprocessing library regex-posix-0.95.2... /usr/local/bin/hsc2hs: line 29: /usr/local/lib/ghc-7.10.3/bin/hsc2hs: No such file or directory Failed to install regex-posix-0.95.2 cabal: Error: some packages failed to install: regex-compat-0.95.1 depends on regex-posix-0.95.2 which failed to install. regex-posix-0.95.2 failed during the building phase. The exception was: ExitFailure 127 jeff@jeffLenovUbu:~/dwt_git_hask$ As an example of a stack problem, I downloaded Oleg Prophet's implementation of MicroKanren [1]. "stack build" ran without complaint (or visible output), but "stack ghci" fails thus: jeff@jeffLenovUbu:~/work/computer/Haskell/microKanren/featherweight$ stack ghciConfiguring GHCi with the following packages: microKanren GHCi, version 7.10.2: http://www.haskell.org/ghc/ :? for help <command line>: cannot satisfy -package QuickCheck (use -v for more information) jeff@jeffLenovUbu:~/dwt_git_hask$ stack ghci even fails (with a different error) on my own project [2]: jeff@jeffLenovUbu:~/dwt_git_hask$ stack ghci Configuring GHCi with the following packages: Dwt GHCi, version 7.10.2: http://www.haskell.org/ghc/ :? for help <command line>: can't load .so/.DLL for: /home/jeff/dwt_git_hask/.stack-work/install/x86_64-linux/nightly-2015-08-03/7.10.2/lib/x86_64-linux-ghc-7.10.2/Dwt-0.1.0.0-7VW1kKp7le6K6OdeGoRsDt/ libHSDwt-0.1.0.0-7VW1kKp7le6K6OdeGoRsDt-ghc7.10.2.so (/home/jeff/dwt_git_hask/.stack-work/install/x86_64-linux/nightly-2015-08-03/7.10.2/lib/x86_64-linux-ghc-7.10.2/Dwt-0.1.0.0-7VW1kKp7le6K6OdeGoRsDt/ libHSDwt-0.1.0.0-7VW1kKp7le6K6OdeGoRsDt-ghc7.10.2.so: undefined symbol: Dwtzu7VW1kKp7le6K6OdeGoRsDt_DwtziSearch_QNode_con_info) jeff@jeffLenovUbu:~/dwt_git_hask$ Thanks in advance for your help. [1] https://github.com/Oregu/featherweight [2] https://github.com/JeffreyBenjaminBrown/digraphs-with-text -- Jeffrey Benjamin Brown