Thanks, everybody!Your feedback is a great food for my mind (as Lewis Carroll once wrote :)
When asking "how to implement cache in Haskell" I was hopping that there exists some solution without using Data.Array, more "functional" approach, if I may say so ...
I must be wrong, though (need more time to fully comprehend solution that Steven described in this thread ).
On Thu, Apr 14, 2011 at 3:22 PM, Ryan Ingram
<ryani.spam@gmail.com> wrote:
So if we were to emulate your Java solution, we'd do
import Data.Array
cacheSize :: Int
cacheSize = 65536
table :: Array Int Integer
table = listArray (1,cacheSize) (1 : map go [2..cacheSize]) where
go n
| even n = 1 + lookup (n `div` 2)
| otherwise = 1 + lookup (3 * n + 1)
lookup :: Integer -> Integer
lookup n
| n < cacheSize = table ! (fromInteger n)
| even n = 1 + lookup (n `div` 2)
| otherwise = 1 + lookup (3 * n + 1)
The rest of the code is just some simple i/o.
The table is filled up lazily as you request values from it.
--
All the best,
Dmitri O. Kondratiev
"This is what keeps me going: discovery"
dokondr@gmail.com
http://sites.google.com/site/dokondr/welcome