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 <daniel.is.fischer@googlemail.com> wrote: From: Daniel Fischer <daniel.is.fischer@googlemail.com> Subject: Re: [Haskell-cafe] Reader monad To: haskell-cafe@haskell.org Cc: "michael rice" <nowgate@yahoo.com> Date: Wednesday, December 29, 2010, 2:47 PM On Wednesday 29 December 2010 19:30:11, michael rice wrote:
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.