The reader monad is so complex and seems to be useless. In an imperative language like Java or C++, there is no equivalent concept for the reader monad, if I am not mistaken. Can you give me a sim...

I'm reading PureScript by Example and got to the part introducing the Reader monad. The example goes like this: createUser :: Reader Permissions (Maybe User) createUser = do permissions <- ask...

When I design my programming model I always have a dilemma which approach is better: type MyMonad1 = StateT MyState (Reader Env) type MyMonad2 = ReaderT Env (State MyState) What are the benefits a...

Having read http://learnyouahaskell.com/functors-applicative-functors-and-monoids#applicative-functors , I can provide an example of the use of functions as applicative functors: Let's say res is ...

I'm pulling together code from a number of different places, and I'm trying to deal with the following: Problem I have a transformer stack with the following simplified type: action :: m (Reader...

When learning the Reader Monad, I find that it is defined as: newtype Reader r a = Reader { runReader :: r -> a } instance Monad (Reader r) where return a = Reader $ \_ -> a m >>= k...

The canonical 'Monad instance' for environment sharing plus nondeterminism is as follows (using pseudo-Haskell, since Haskell's Data.Set isn't, of course, monadic): eta :: a -> r -> {a} -- '...

I'm learning category theory. I understand the concept of reader monad, it's even pretty easy to implement: case class Reader[DEP, A](g: DEP => A) { def apply(dep: DEP): A = g(dep) def map[...

Why is there a Reader monad and a MonadReader monad in Control.Monad.Reader? The package documentation talks about the Reader monad and then launches into the MonadReader documentation directly wit...

I wrote the following code. It is working and using the Reader monad. Could you give me some hints about code style in Haskell ? Mainly, I mean monads -- I am newbie. import Control.Monad.Reader...

In Scalaz Kleisli[F, A, B] is a wrapper for A => F[B]. ReaderT[F, A, B] -- reader monad transformer -- is just an alias of Kleisli[F, A, B]. Reader[A, B] monad is a specialization of Reader...

I've got some code that looks sort of like this, ignoring all the code that isn't relevant to my question: import qualified Control.Monad.Reader as Reader data FooEnv = FooEnv { bar :: Int -&gt...

I'm trying to understand the actual need for the reader and/or state monads. All the examples I've seen (including many on stackoverflow as I've hunted for suitable examples I can use and in variou...

I've had a look at the algo.monads and fluokitten documentation. I've also read through monad blog entries by Jim Duey, Konrad Hinsen and Leonardo Borges. The only reference I can find to the Rea...

I have the following code that uses the Reader monad for configuration and also has to deal with IO[Option[String]] and I've ended up with code that stair-steps in my encode function. How can I fo...

just looking for an explanation how does following composition work: (=<<) . return where (=<<) :: (a -> m b) -> m a -> m b return :: a -> m a (.) :: (b -> c) -> (...

How do I create a properly functional configurable object in Scala? I have watched Tony Morris' video on the Reader monad and I'm still unable to connect the dots. I have a hard-coded list of Cli...