Re: [Haskell-beginners] Laziness, automatic memoization and arrays

On Sat, Aug 27, 2011 at 07:03:00PM -0400, Oscar Picasso wrote:

Hi,

I have a very simple question about laziness, memoization and arrays. If I have:

import Data.Array

a = listArray (1,10) $ map (\x -> (x*x)) [1..10]

main = do print c ! 4 print c ! 4 print c ! 4

Can we assume that the operation 4 * 4 is evaluated only once, when first calling print c ! 4 in the main method?

Yes. Any value with a name (such as c in your example) will only be evaluated once, no matter how many times you refer to it. -Brent