Changing the dependency isn't enough. You also want to bump the version number (say, A.B.C.D into A.B.C.D.1) and make your project depend on the bumped version. This way cabal wont find that version anywhere but in installed database and will continue just fine.

If the library works fine under base-4 you might also contact the developer so that he can upload the new version which will allow you to drop that hack altogether.

Working with such locally-changed versions can be easier if you try cabal-devel tool or similar.

But I think might consider another solution: don't use that library. As HDBC docs says:

ODBC

Available from http://software.complete.org/hdbc-odbc. Or, to partitipace in development, use git clone git://git.complete.org/hdbc-odbc

MySQL

MySQL users have two choices: the first is the ODBC driver, which works and has been tested against MySQL on both Linux/Unix and Windows platforms. There is also an alpha-quality native MySQL driver available for download at http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HDBC-mysql with a homepage at http://www.maubi.net/~waterson/hacks/hdbc-mysql.html.

So clearly, HDBC developer(s?) think that HDBC-odbc is the way.

Best regards,

Krzysztof Skrzętnicki

On Sat, Apr 2, 2011 at 00:46, Alexey G <kreed131@gmail.com> wrote:

Hello. I have some trouble with HDBC-mysql package (http://hackage.haskell.org/package/HDBC-mysql).
It depends on base (<4), but in GHC 7 - base 4.3.1.
I download a HDBC-mysql package and change dependence in .cabal file to base (<5). It works fine.
But I want to build another package that depend on HDBC-mysql and cabal check dependencies from the hackage, where is HDBC-mysql depend on base (<4).

What I should do?

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