Where is the data constructor for 'State'?

Question

After reading a couple of tutorials on Haskell state monads I wanted to try them out myself. The tutorials I read claim that the Control.Monad.State provide the following defini

Answer 1

I am working through Learn You A Haskell (LYAH), and I thought that I would post the working version of the example code found at http://learnyouahaskell.com/for-a-few-monads-more#state (Chapter 13, Section "Tasteful stateful computations")

The code that no longer works:

import Control.Monad.State  

pop :: State Stack Int  
pop = State $ \(x:xs) -> (x,xs)  

push :: Int -> State Stack ()  
push a = State $ \xs -> ((),a:xs)  

The code modified to work:

import Control.Monad.State 

pop :: State Stack Int
-- note the change from "State" to "state"
pop = state $ \(x:xs) -> (x,xs)

push :: Int -> State Stack ()
push a = state $ \xs -> ((), a:xs)

The "stackManip" function works as is:

stackManip :: State Stack Int  
stackManip = do  
    push 3  
    a <- pop 
    pop