I use them fairly heavily, mostly so I can make packages that work with arbitrary transformer stacks. I'd be willing to endure the pain of using #if MIN_VERSION_transformers(x,y,z) bracketing around the use of Strict.WriterT and Strict.RWST constructors so long as there were writerT/runWriterT and rwsT/runRWST analogues I could simply invoke. -Edward On Tue, Mar 19, 2013 at 11:07 AM, Gabriel Gonzalez wrote:

Presumably we'll also need

...

writerT :: m (a, w) -> WriterT w m a

Yes, we would need that, too:

writerT m = WriterT $ \w -> do (a, w') <- m let wt = mappend w w' wt `seq` return (a, wt)

Is there any reason to keep Control.Monad.Trans.Writer.**Strict, or

...

should this replace it?

If we replace the old one, it will break existing code that used the `WriterT` constructor. Same thing for the strict RWST constructor if we similarly modify that. However, I don't know exactly how many packages use those constructors. I will try to do a text search of Hackage this coming weekend to check and see if it is feasible to ask downstream packages that use `WriterT`/`RWST` constructors to set upper bounds on `transformers`.

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