Work with mutable arrays in haskell examples

marrays.hs

-- video https://youtu.be/uj2N5fBZnCA
import Data.Array.MArray
import Data.Array.IO.Internals (IOArray(IOArray))
import Control.Monad.ST
import Data.Array.ST

workio = do
         a <- newArray (0,3) 'a' :: IO ( IOArray Int Char)
         writeArray a 3 'x'
         a_ <- getAssocs a
         print a_

         e <- readArray a 3
         print e

workst = do
           a <- newArray (0,3) 'a' :: ST s (STArray s Int Char)
           writeArray a 3 'x'
           getAssocs a

main = workio >> print (runST workst)

--Some links:
--https://www.haskell.org/tutorial/arrays.html
--https://mmhaskell.com/data-structures/array
--https://wiki.haskell.org/Arrays   

video https://youtu.be/uj2N5fBZnCA