I am (again) running into cabal install issues; which have been all too common for me. In this case as an example, I tried this: C:\Users\haskell>Cabal install buildwrapper ..... buildwrapper-0.6.0 depends on regex-tdfa-1.1.8 which failed to install. regex-tdfa-1.1.8 failed during the building phase. The exception was: ExitFailure 1 So I tried this: C:\Users\haskell>cabal install regex-tdfa Resolving dependencies... In order, the following would be installed: regex-base-0.93.2 (reinstall) changes: array-0.3.0.2 -> 0.4.0.0, base-4.3.1.0 -> 4.5.0.0, bytestring-0.9.1.10 -> 0.9.2.1, containers-0.4.0.0 -> 0.4.2.1, mtl-2.0.1.0 -> 2.1.2 regex-tdfa-1.1.8 (new package) cabal: The following packages are likely to be broken by the reinstalls: regex-posix-0.95.1 regex-compat-0.95.1 haskell-platform-2011.3.0.0 regex-posix-0.94.4 regex-compat-0.93.1 haskell-platform-2011.2.0.1 regex-posix-0.95.1 regex-compat-0.95.1 haskell-platform-2012.2.0.0 Use --force-reinstalls if you want to install anyway. So what to do? Last time I got into a situation like this I tried to start-over with cabal, remove all local cache and rebuild the library.

From a suggestion in SO; delete the ~/ghc & ~/cabal files and restart cabal, by a "cabal install cabal-install".

Didn't help much, still stuck. Any hints? I find that library issues like this with cabal are the biggest time-soak I have with using Haskell, and I usually have to abandon attempts to try some new library for various examples. "Ghc-pkg check" lists lots of warnings, but all from haddock-html or haddock-interface; not sure what to make of that but I think it just means that somehow documentation was not installed for these packages.

...

cabal -V cabal-install version 0.14.0 using version 1.14.0 of the Cabal library GHCi version 7.4.1 HaskellPlatform-2012.2.0.0