Haskell 状态 Monad 语法

Question

What is the Syntax to test this code sample in haskell?

type Estate1 x = ([Int], Map x Int)

pop :: State (Estate1 Int) Int
pop = do
  (liste,key) <- get
  return ((Map.!) key 1)

Answer 1

runState pop ([1,2,3], Map.singleton 1 42)
              ^^^^^^^^^^^^^^^^^^
                 initial state

Try it in ghci, you'll see what it returns.