Data instances for MTL types

[Ross Paterson]

On Thu, Jan 15, 2009 at 10:46:46PM +0100, Henning Thielemann wrote:
>
> When trying to perform some tests with StrictCheck, I found that the  
> monads from the 'transformers' package don't have Data instances. Can 
> they be provided while keeping 'transformers' Haskell 98 and avoiding 
> orphan instances?

The Typeable and Data instances will be non-trivial, as they can't be
derived for higher-order type constructors.