No it is not.
Upgrading to Xcode 5 will break a whole mess of things. (A common one is Cabal installs)
GHC 7.6.x does not now how to use clang for a preprocessing step and it will break.
Do not upgrade to Xcode 5 until GHC 7.8 is released.
I did this before I started learning haskell and it was not a fun experience trying to figure out what went wrong when I tried to download cabal packages and ghc generated a 4000 line error code.
See: http://haskell.org/pipermail/haskell-cafe/2013-September/108902.html
If anyone who has already downloaded Xcode 5 stumbles upon this after everything breaks, the way to fix your bug is:
- Download the Xcode 4.6.x command line tools from the apple developer website.
- Install
- Write some killer Haskell