[Haskell-cafe] strange behavior of GHC 7.8.2

Kazu Yamamoto (=?iso-2022-jp?B?GyRCOzNLXE9CSScbKEI=?=) kazu at iij.ad.jp
Mon Jul 7 07:58:31 UTC 2014

Hi Yuras,

Thank you for your reply.

> I'm 90% sure you have MonadIO and RWST imported from different versions of
> transformers. Try to load the code into ghci and check ':i MonadIO' and ':i
> RWST'. If you'll see fully qualified (including package name and version)
> names somewhere, then that is the issue.
> See also
> http://stackoverflow.com/questions/11068272/acid-state-monadstate-instance-for-update

Yes. Probably MonadIO belongs to transformers while RWST does
to transformers

My question is why this happens. I think that GHCi should use RWST
provided by transformers


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