On 12/12/06, Louis J Scoras
What I didn't realize is that even though the documentation for Control.Monad says that (->(r)) is an instance, it must not be defined there. Importing Control.Monad.Reader indeed does make it work, thanks for pointing that out again.
So I guess my next question would be, looking here
http://haskell.org/ghc/docs/latest/html/libraries/base/Control-Monad.html
How do I figure out that the instance declaration is actually in the Reader module? Is it just because the (->) constructor is special -- or just not hyperlinked?
It's pretty subtle, but the Haddock there does list an instance of MonadReader r ((->) r). In newer GHC's the instance is also found in Control.Monad.Instances. In my opinion, it belongs in the Prelude. :) - Cale