Changes to base

Changes to base:
commit d0b74cac0b0ab5371d15b6f73c0e627b41c3a152
Author: Krzysztof Langner <klangner@gmail.com>
Date:   Wed Jan 1 14:14:46 2014 +0100

    Improve error messages for partial functions in Data.Data

    This closes: #5412