Hi, Daniel.
I had an "Aha!" moment and it all makes sense now. Just as the State monad can hold a generator (which can change) and pass it down a calculation chain, a Reader monad can hold an environment (which doesn't change) and pass it down a calculation chain. I was wondering how I could include a (global) house betting limit in that craps application I've been playing with (without passing it as a parameter) and it sounds like the Reader monad would be an ideal candidate. Correct? It also sounds like a job for monad transforms.
Michael
--- On Wed, 12/29/10, Daniel Fischer
Yes, I'd already noticed that ReaderT preceded Reader. Guess I'll have to check out the Indentity monad too. I hope it's not dependent upon yet another monad.
No, the Identity monad stands alone. And as the name suggests, it's pretty simple.