Hi, I've been updating the various haskell ports in MacPorts and have found a couple of problems with the latest Cabal (1.1.6, as provided by ghc-6.6). One is simply an infelicity that adds unnecessary work: why does ./Setup register fail with an error when used with an application that installs no libraries? Could it simply return success and an informational message like, "No library to install"? As it is, the user (or the person building the package) needs to know if a library is installed or not. It's not a big deal in the case of packages which just provide libraries, but it creates a difference in installation procedure for packages that only provide applications and those that provide applications along with libraries. (For an application, the script version of registration, ./Setup register --gen-script, should just generate a stub that returns success, too.) Having register simply return success for an application also makes the library and application installation procedures identical. From my experience in building packages, the more uniform the installation procedure, the better. The second problem I found is more serious. When installing a library, in this case MissingH 0.16, I get the error: ghc-pkg: /opt/local/lib/MissingH-0.16.0/ghc-6.6/include doesn't exist or isn't a directory (use --force to override) Error: Target com.apple.activate returned: shell command "/opt/local/ libexec/missingh/register.sh" returned error 1 Command output: Reading package info from stdin ... done. ghc-pkg: /opt/local/lib/MissingH-0.16.0/ghc-6.6/include doesn't exist or isn't a directory (use --force to override) Warning: the following items did not execute (for missingh): com.apple.activate Error: Status 1 encountered during processing. crossroads-able> (the above is the output of the MacPorts portfile.) The problem is that when the build is staged into a temporary location so the files can be inventoried, an empty directory, <prefix>/lib/MissingH-0.16.0/ghc-6.6/include is created. MacPorts deletes this empty directory (along with a number of other unused directories it creates in the staging process). The registration process requires the empty directory to be present and fails, as shown above, if it is not. The solution is simple: cabal can to drop a small file into any directory it needs, say ".cabal-turd", preventing it from being deleted (This is most easily done from the cabal side, rather than the packaging system side, since the path has the haskell compiler and version coded into it.) I know that a case can be made for packaging systems preserving all the directories created by a package, even empty ones. However, Macports (formerly darwinports) and cabal played nicely in the past and the 1.1.6 behavior breaks this. Best Wishes, Greg