work with Immutable array in Haskell

iarray.hs

-- video https://youtu.be/RPEtIZ44RSc
import Data.Array.IArray
import Data.Char (toUpper)
-- elements that is associated with some kind of numerical index 
-- truly constant time (O(1)) access. 
-- store their data more efficiently in memory.
-- modification function must create an entirely new array (partially can be fixed with Monad context)


-- math look:
 -- functions from indices to values
 -- to assure efficient, domains must be isomorphic to finite contiguous subsets of the integers.

main = do 
          let a = array (0,2) [(0, 'a'),(1, 'b'),(2, 'c')] :: Array Int Char
          let c = array (1,1) [(1, 'h')] :: Array Int Char
          let b = listArray (0, 2) ['x','y','z'] :: Array Int Char
          let e = a ! 1
          let bs = bounds a
          let es = elems a
          let is = indices a
          let pas = assocs a
          let ua = amap toUpper a
          let ub = ixmap (0,1) (+1) b
          print a
          print b
          print e
          print bs
          print es
          print is
          print pas
          print c
          let d = a // (assocs c)
          print d
          print ua
          print ub
          
          
--Some links:
--https://www.haskell.org/tutorial/arrays.html
--https://mmhaskell.com/data-structures/array
--https://wiki.haskell.org/Arrays          

video https://youtu.be/RPEtIZ44RSc