#4159: move Monad and MonadFix instances for Either from mtl to base

David Waern david.waern at gmail.com
Tue Jun 29 11:16:42 EDT 2010

2010/6/29 Ross Paterson <ross at soi.city.ac.uk>:
> The proposal is to move the Monad and MonadFix instances for Either
> (currently in the mtl package) to Control.Monad.Instances and
> Control.Monad.Fix respectively (both in the base package).  The Monad
> instance is still an orphan, to retain Haskell 98 compatibility, but the
> MonadFix instance is together with its class.  The Error constraint is
> removed from both instances, and the default definition of fail is used.



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