Trying to move a do block within a case assignment

docase.hs

someMaybe :: UserID
someVariable :: Html

simpleRenderFunction :: (Int -> String) -> Html

-- For example, string is a user name: is this a known user?
testCondition :: MonadIO m => String -> m Bool
-- Takes into account the result from the testCondition function.
complicatedRenderFunction :: (Int -> String -> Bool) -> Html
complicatedRenderFunction a s b = case b of ....

------ The way it was done before:
isThisAUser <- testCondition "User1"
let someVariable = complicatedRenderFunction 200 "Hello" isThisAUser
---------

----- Attempted refactor
let someVariable = case someMaybe of 
    Nothing -> 
        simpleRenderFunction 200 "Hello"
    Just someValue ->
        -- evaluate the test condition and use it in the assignment?
        testCondition "User1"   >>= complicatedRenderFunction 200 "Hello" 
        -- Evaluates to a bool      -- Partially applied, only bool argument needs to be filled?