Haskell: execute IO action and extract value inside list comprehension

Question

I am trying to generate a list of randomized boolean values based on a moving threshold.

This is my code. The function at issue is isActionRandom :

randomBool :: Int -> IO Bool
randomBool p = do n <- randomRIO(1,100)
              return (if n > p then True else False)

isActionRandom :: Float -> Int -> Int -> Int -> IO [Bool]
isActionRandom eps n m step = [ randomBool (floor (eps-(0.01*y) * 100))
                            | x <- [1..(n*m)]
                            , y <- floor(x/(m*step))]

isActionRandom does not compile because the list created is type [IO Bool] and not IO [Bool] as I intended. How do I "extract" the boolean value from the IO function at each iteration, and build a list of the intended type?

Answer 1

You can use the sequence method from Traversable :

sequence :: (Traversable t, Monad m) => t (m a) -> m (t a)

In your case, it will have the type:

sequence :: [IO Bool] -> IO [Bool]