Re: mtl, transformers, and monads-fd are in an unhappy place

Bryan O'Sullivan schrieb:

Hi, gents -

I've lately been writing some application code that, by virtue of the libraries it uses, depends on both mtl and monads-fd. Alas, this means that I have two incompatible versions of some of the most widely used monad transformers in scope, and I have to carefully import the right version of Control.Monad.Trans:

{-# LANGUAGE PackageImports #-} import qualified "mtl" Control.Monad.Trans as M import qualified "monads-fd" Control.Monad.Trans as F

In transformers-0.2 the module Control.Monad.Trans was split into Control.Monad.Trans.Class and Control.Monad.IO.Class. Thus if the transformers-dependent packages switch to transformers-0.2 you do not need PackageImports.