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You can reach the person managing the list at beginners-ow...@haskell.org When replying, please edit your Subject line so it is more specific than "Re: Contents of Beginners digest..." Today's Topics: 1. Stack overflow folding a map (tcollin371) ---------------------------------------------------------------------- Message: 1 Date: Sat, 16 Feb 2013 04:13:14 -0500 (EST) From: tcollin371 <tcollin...@earthlink.net> Subject: [Haskell-beginners] Stack overflow folding a map To: Hask <beginners@haskell.org> Message-ID: <3549819.1361005995070.javamail.r...@elwamui-muscovy.atl.sa.earthlink.net> Content-Type: text/plain; charset=UTF-8 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 ------------------------------ _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners End of Beginners Digest, Vol 56, Issue 28 *****************************************