On Wed, Nov 19, 2008 at 03:06:04PM +0100, Stefan Holdermans wrote:
Could anyone confirm the following claims?
* base-3.0.3.0 (shipped with GHC 6.10.1) is supposed to be backwards compatible with base-3.0.2.0 (shipped with GHC 6.8.3) ...
Yes.
* ... but it isn't! (For example, the Arrow class from Control.Arrow is a subclass of Category from Control.Category in base-3.0.3.0, but not in base-3.0.2.0.)
Yes. It wasn't possible to handle this change in a compatible way, I'm afraid.
Do we know of any similar issues?
I think the Arrow/Category changes are the only issue. I think one of the methods moved from one class to the other as well.
What's the recommended workaround when shipping code that is to support both GHC 6.8.* and GHC 6.10.*?)
CPP is the best solution I can think of. Thanks Ian