MTL vs Transformers. Any status update?

Thomas DuBuisson thomas.dubuisson at
Sat Nov 28 16:11:46 EST 2009

On Sat, Nov 28, 2009 at 8:56 AM, Ross Paterson <ross at> wrote:
> On Sat, Nov 28, 2009 at 04:40:49PM +0000, Duncan Coutts wrote:
>> Could someone remind me why it's better for use to ask everyone to
>> switch to monads-fd / transformers rather than to mtl-2? Does that make
>> the transition easier?
> The problem is that transformers and mtl use the same module names,
> such as Control.Monad.Identity.  Unless one of these packages is hidden,
> people using ghci or ghc --make will have problems.

I've happily used LANGUAGE PackageImports to handle transformer / mtl
conflicts.  I don't see why either one must change their module names
and there are obvious disadvantages.


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