I didn't get any concrete remedy for this, or its underlying cause. Does it mean that this package is incompatible with others currently installed, and I am supposed to make a choice to uninstall or break them by forcing this, or ...??? -------------------------------------------
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?
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