On Wed, Feb 25, 2009 at 12:53 AM, Henning Thielemann
<[email protected]> wrote:

> Thanks for your interest in data-accessor ...

It's a very useful package! My previous email was written in haste,
I should have mentioned how much the template-haskell stuff saved
effort in boilerplate.

>
> On Tue, 24 Feb 2009, Jean-Philippe Bernardy wrote:
>
>> I see that the types of some functions are more specific in the new
>> data accessor package, this
>> causes breakage in the yi project: effectively we cannot update to
>> 0.2, but we depend on packages
>> that may have a laxer dependency.
>
> What functions do you mean? I'm not aware that I have specialised some
> function types. I have however rewritten the MonadState part from 'mtl'
> package to 'transformers'. Is this your problem?

I guess it is related. It is possible that I do not know how to use
'transformers' properly.
Specifically:

http://hackage.haskell.org/packages/archive/data-accessor/0.1.4/doc/html/Data-Accessor.html

getA :: MonadState r m => Accessor r a -> m a

http://hackage.haskell.org/packages/archive/data-accessor/0.2.0.2/doc/html/Data-Accessor.html

getA :: Monad m => Accessor r a -> StateT r m a

I'd rather not rewrite the monads to the StateT form...
I'm now writing a compatibility layer, but I feel it would be better if
 the data-accessor package supported the old interface.

Thanks!
-- JP

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