I unregistered the previous install with ghc-pkg unregister (for mysql and mysql-simple) and I tried:
Resolving dependencies...
Configuring mysql-0.1.1.7...
Building mysql-0.1.1.7...
Failed to install mysql-0.1.1.7
Last 10 lines of the build log ( /Users/batman/.cabal/logs/mysql-0.1.1.7.log ):
Building mysql-0.1.1.7...
Preprocessing library mysql-0.1.1.7...
dyld: Library not loaded: libmysqlclient.18.dylib
Referenced from: /private/var/folders/fk/339860r16j759wmsfmjkyr4h0000gn/T/mysql-0.1.1.7-25273/mysql-0.1.1.7/dist/build/Database/MySQL/Base/C_hsc_make
Reason: image not found
running dist/build/Database/MySQL/Base/C_hsc_make failed (exit code -5)
command was: dist/build/Database/MySQL/Base/C_hsc_make >dist/build/Database/MySQL/Base/C.hs
cabal: Error: some packages failed to install:
mysql-0.1.1.7 failed during the building phase. The exception was:
ExitFailure 1