transformers versus mtl

Sittampalam, Ganesh ganesh.sittampalam at
Mon Mar 16 04:48:34 EDT 2009

Henning Thielemann wrote:
> On Sun, 15 Mar 2009, Sittampalam, Ganesh wrote:
>> I see that the initial version of the Haskell Platform is planning to
>> use mtl because of its status in extralibs - but if transformers is
>> the way forward, then perhaps this should be changed?
> I prefer transformers + monad-fd + monad-tf or whatever as the
> standard implementation over mtl. 

Yes, so do I.

>> What are the relative status of transformers and mtl? Are we trying
>> to deprecate mtl use in favour of transformers (+ appropriate
>> dependencies like monads-fd)?
> I have actually done this step in all of my packages.

I think this makes perfect sense where the monad transformer types are
not externally visible. I'm just concerned about what to do with
where the types are part of the interface - it would be best to
this to some extent to avoid incompatibilities.



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