How to take out a value out of a monad in Haskell?

Question

Is there any way to take \"things\" out of a monad?

I am developing a game, and I am now trying to understand about databases. I found happstack really nice, but I

Answer 1

After elems <- query GetThings the elems is [Thing] so <- inside do is about getting things out of monad (called bind operation). The last statement return put things inside a monad. So either you can call you other function after getting elems and before return or where ever you are calling getAllThings you can use extract the value using <- from the monad and pass it to your function

Answer 2

You are not supposed to exit IO monad this way (except unsafePerformIO function), but you can still use your function inside it:

process :: MonadIO m => m ()
process = do
          elems <- getAllThings
          let smth = doSomeThingWithThings elems
          -- ...