Get list of two columns from SQLite result when using Database.SQLite

I am asking here second time today.

There is a function isFileInstalled which passes parameter f to execParamStatement as parameter. The problem is that when it's called with parameter f == "/usr/bin/getpkg" (or another) it's not exiting application when there is row with path == f.

Also, when exiting a message should appear. To do this I need to read owner and path columns.

How can I do this? Can you write an examl

isFileInstalled f = do
            dbcon <- openReadonlyConnection "/var/lib/beaver/pkgs.db"
            res <- execParamStatement dbcon "SELECT * FROM files WHERE path = :path" [(":path", f)] :: IO (Either String [[Row Value]])
            when (null res) (return ())
            putStrLn ("File " ++ res ++ " is already installed and comes from " ++ res ++ ".") -- first res is `owner` and second is `path`
            closeConnection dbcon
            exit

files table:

owner     | path
------------------------------
getpkg.py | /usr/bin/getpkg
getpkg.py | /usr/bin/getpkg.py