transformers 0.4: change in accessor function exports?

Henning Thielemann schlepptop at
Wed May 7 13:31:11 UTC 2014

Am 07.05.2014 13:43, schrieb Michael Snoyman:

> In the case here, the syntax:
>      import Control.Monad.Trans.Reader (ReaderT (..))
> is very convenient. But it's true that you don't really gain much from
> the distinction between these two:
>      import Control.Monad.Trans.Reader (ReaderT (ReaderT, runReaderT))
>      import Control.Monad.Trans.Reader (ReaderT (ReaderT), runReaderT)
> Perhaps the latter should be considered a better approach, since it's
> more resilient to changes in datatypes.

However, even if imported in the second way, runReaderT identifier can 
be used in record field update syntax. I guess it would be more 
consistent to allow only the use as a function when imported like an 
ordinary function.

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