Don Stewart wrote:
default(Int)
divisors i = filter (\j -> i `rem`j == 0) (enumFromTo 1 (i-1)) main = print $ filter (\i -> i == sum (divisors i)) (enumFromTo 1 10000)
...
So almost identical types to the C program (bar for the return [Int]).
Finally, we can manually translate the C code into a confusing set of nested loops with interleaved IO,
how lazy is `print` supposed to be? If it's strict, we need to return / accumulate a list (and in this case, that is not very time-consuming because there are only four numbers in the list) from http://haskell.org/onlinereport/standard-prelude.html print x = putStrLn (show x) show on lists is lazy and doesn't matter that it's not for Ints putStrLn :: String -> IO () putStrLn s = do putStr s putStr "\n" putStr :: String -> IO () putStr s = mapM_ putChar s okay, mapM_ makes it lazy. putChar :: Char -> IO () putChar = primPutChar (It's easy to get confused with OS buffering effects too...) so it should ALL be able to fuse, with no intermediate lists, I think (not sure about [Char] from show... or whether fusion works with IO sequencing...) Isaac