deprecating Error class (Was: Proposal: add handleError to mtl)

Henning Thielemann lemming at
Thu Jun 6 13:00:06 CEST 2013

On Thu, 6 Jun 2013, Roman Cheplyaka wrote:

> * Henning Thielemann <lemming at> [2013-06-06 12:14:10+0200]
>> On Wed, 5 Jun 2013, Ross Paterson wrote:
>>> On the subject of ErrorT, I wonder if it's time to deprecate the Error class.
>> Since I think ErrorT gives the wrong association with the 'error'
>> function, I would prefer to give up the Control.Monad.Trans.Error
>> module entirely and start a new module Control.Monad.Trans.Exception.
> ... which would give the wrong association with exceptions (in the
> Control.Exception sense). I don't see how this is an improvement.

It's the better association and it is already mentioned in the module 
description of Control.Monad.Trans.Error:

"This monad transformer adds the ability to fail or throw exceptions to a 

Nonetheless, you may suggest another module name. Independent from the 
name of a new module, I would suggest to deprecate the Error name instead 
of removing something from the Error module.

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