Hello SimonK77, Thursday, August 27, 2009, 11:24:14 PM, you wrote: for linear timing it needs memoization of previous results. haskell compilers doesn't do it automatically since it may change space properties of program. well-known example is: main = print (sum[1..1000] + prod[1..1000]) in order to use memoization you should declare fib as array: fib = array (1,999) ([1,1]++map (\i -> fib!(i-1) + fib!(i-2)) [3..999])
Hallo everyone, as Haskell uses the Lazy Evaluation reduction policy also known as Outermost Graph Reduction, I was wondering if the following simple implementation of the Fibonacci sequence would result in linear runtime behaviour. fib :: Integer -> Integer fib 0 = 0 fib 1 = 1 fib n = fib (n - 2) + fib (n - 1) Is the following reduction sequence realistic, or am I admitting to much intelligence to the Haskell Compiler? I hope someone can help...
View this message in context: Reduction Sequence of simple Fibonacci sequence implementation Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com.
-- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com