[1] might help you. [1] - http://www.haskell.org/haskellwiki/Foldr_Foldl_Foldl%27 Mateusz K. On 16/02/13 09:13, tcollin371 wrote:
I've been playing around with Haskell on and off for a while, and am getting a "Stack space overflow" that I can't seem to correct. I have a map containing about 2 million items. Actually, it's a map keyed off of an Int where the element is another map keyed off of a string that has three Ints as its data. The number of top level maps is pretty small (< 50), and the maps held by them hold a lot of entries.
I want to walk through all of the entries and gather some statistics, but I keep getting the stack overflow. I worked down my test to an inner and outer fold that just counts the entries, and I still get the stack overflow. I added 'seq' calls to make sure that the count isn't building up a bunch of undone operations, and I'm using foldlWithKey, and have also tried foldlWithKey' with the same result.
I get the count in my main function and immediately print it out. Here is the relevant code:
outputIfNotFilteredCount1 :: Int -> KeyMap -> PuzzleMapRecord -> Int outputIfNotFilteredCount1 inCount key entry = seq inCount (inCount + 1)
outputDatabaseCount1 :: Int -> Int -> InnerDB -> Int outputDatabaseCount1 inCount smndCount innerDB = seq inCount (inCount + outCount) where outCount = Map.foldlWithKey' outputIfNotFilteredCount1 0 innerDB
main = do ... let count = Map.foldlWithKey' outputDatabaseCount1 0 resultDB putStrLn $ "Database entries:" ++ (show count)
Any thoughts on why this is running out of stack space?
-Truman
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