Re: MTL vs Transformers. Any status update?

On Sat, 28 Nov 2009, Thomas DuBuisson wrote:

On Sat, Nov 28, 2009 at 8:56 AM, Ross Paterson wrote:

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On Sat, Nov 28, 2009 at 04:40:49PM +0000, Duncan Coutts wrote:

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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.

Is there long-term value in having both packages, if mtl ends up as just re-exporting pieces of transformers+monads-fd? I guess it reduces the dependencies people have to declare, but that seems marginal to me. Ganesh