Error - C Stack Overflow Haskell
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down vote favorite I'm working on parsing a CSV file into a CSV type which is a list of Record which is a list of Field, which are just Strings. After inserting a new row and then trying to access the csv I get the c stack overflow error. I'v read this error may come from too large a "thunk" by using tail recursion but I don't think thats stackoverflow haskell what I'm doing wrong? type CSV = [Record] type Record = [Field] type Field = String run :: IO() run = do inFile <- readFile "myFile.csv" let csv = parse inFile let csv = (insertRow "abc,def,ghi" csv) putStr (show csv) insertRow :: String -> CSV -> CSV insertRow newRow csv = csv ++ [toRecord newRow] parse :: String -> CSV parse file = map toRecord (parseLines file "" []) toRecord :: String -> Record toRecord line = parseWords line "" [] -- parseLine input partialCSV records parseLines :: String -> String -> [String] -> [String] parseLines [] partial records = records ++ [partial] parseLines ('\r':xs) partial records = parseLines xs [] (records ++ [partial]) parseLines (x:xs) partial records = parseLines xs (partial ++ [x]) records -- parseWords input partialRecord fields parseWords :: String -> String -> [String] -> [String] parseWords [] partial fields = fields ++ [partial] parseWords ('"':xs) partial fields = parseQuotes xs partial fields parseWords (',':xs) partial fields = parseWords xs [] (fields ++ [partial]) parseWords (x:xs) partial fields = parseWords xs (partial ++ [x]) fields parseQuotes :: String -> String -> [String] -> [String] parseQuotes ('"':xs) partial fields = parseWords xs [] (fields ++ [partial]) parseQuotes (x:xs) partial fields = parseQuotes xs (
are possible causes of "C stack overflow" in Hugs? Messages sorted by: [ date ] [ thread ] [ subject haskell stack overflow ] [ author ] On Wed, 04 Feb 2004 23:00:50 +0000 haskell strict foldl Graham Klyne
you have provoked can hopefully help you to diagnose your particular problem. This page shows some code fragments, in red, followed by the error message they provoke, in blue, and https://www.cs.kent.ac.uk/people/staff/sjt/craft2e/errors/allErrors.html an explanation of the source of the problem. You can search for particular errors by https://www.well-typed.com/blog/2014/05/understanding-the-stack/ giving keywords. Please mail me with any examples which you would like to be included in the list Thanks to Daniel Barie, Eerke Boiten, Jane Chan, Rodger Hayes, Brian Herlihy, Ralf Hinze, Stefan Kahrs, Tom Kaiser, Richard O'Keefe and the students on the functional programming courses at the University of Kent for contributing many of these stack overflow errors. 3 'div' 4 ERROR: Improperly terminated character constant The problem here is the use of the wrong sort of quotes. To turn a function, which is written before its arguments, into an operator, which is written between its arguments, you need to enclose it in backquotes. The backquote is round on the same key as the tilde on US keyboards (commonly the top left hand corner of the main block, c stack overflow just above TAB). data BTree a = EmptyBTree | Node a (BTree a) (BTree a) card :: BTree a -> Integer card EmptyBTree = 0 card (Node x) lt rt = (height lt) + (height rt) + 1 ERROR: Equations give different arities for "card" Incorrect bracketing causes the problem here. It looks as though card is a one argument function (arity 1) from the first equation in the definition, and as though it's a three argument function from the second. The misplaced closing bracket is the culprit, and a correct version of the code says card (Node x lt rt) = (height lt) + (height rt) + 1 >maxFour :: Int -> Int -> Int -> Int -> Int >maxFour >| a >= b && a >= c && a >= d = a >| b >= c && b >= d= b >| c >= d = c >| otherwise = d ERROR "test.lhs" (line 3): Undefined variable "a" The definition of maxFour has its variables missing. The second line should read maxFour a b c d. >exOr :: bool -> bool -> bool >exOr b1 b2 >= (b1 && not b2) || (b2 && not b1) ERROR "test.lhs" (line 3): Declared type too general *** Expression: exOr
consisted of a 700 line Haskell program with a complaint that “it deadlocks”. After studying the code I concluded that, for the sake of the bug report, it could be summarized as print a bunch of stuff, then crash with a stack overflow So I wanted to replace the original code with code that did just that: print a bunch of stuff, then crash with a stack overflow. No big deal: {-# LANGUAGE CPP #-} module Main (main) where go :: Int -> IO Int go n = do if (n `rem` THRESHOLD == 0) then putChar '.' else return () n' <- go (n + 1) return (n + n') main :: IO () main = print =<< go 0 The function go prints a dot every THRESHOLD recursive calls; we have a (dummy, since it can never be reached) addition after the recursive call to ensure that go is not tail recursive and will eventually run out of stack space. The THRESHOLD macro variable is there so that we can tweak how quickly the program runs out of stack space, or in other words, how many dots it prints before it crashes. For example, if we compile the code with ghc -O1 PrintThenCrash.hs -fforce-recomp -DTHRESHOLD=23 it prints 22,126 dots before crashing; if we compile with ghc -O1 PrintThenCrash.hs -fforce-recomp -DTHRESHOLD=26 it prints 19,483 dots before crashing. But as I was experimenting to find the right value