It seems that saxParse from Text.XML.HaXml.SAX will successfully parse a malformed XML document. Notice that the SubElem opening and closing tag are not matched in the XML document below. --- input.xml --- <RootNode> <ElemOne> <SubElem attr="foo">element data</SubElemBroken> <NoDataElem/> <ElemOne> </RootNode> --- end input.xml --- The Haskell code below runs without error. It prints out the type of elements found during the parse. --- Haskell Code --- module Main where import qualified Text.XML.HaXml.SAX as SAX import Data.Maybe main = let inputFilename = "input.xml" in do content <- readFile inputFilename let (elements, error) = SAX.saxParse inputFilename content if isNothing error then mapM_ putStrLn (summarizeElements elements) else putStrLn $ "ERROR:" ++ (fromJust error) summarizeElements :: [SAX.SaxElement] -> [String] summarizeElements elements = map summarizeElement elements summarizeElement :: SAX.SaxElement -> String summarizeElement element = case element of (SAX.SaxDocTypeDecl d) -> "DocType" (SAX.SaxProcessingInstruction p) -> "Processing Instruction" (SAX.SaxComment s) -> "Comment" (SAX.SaxElementOpen name attrs) -> "Element Open" (SAX.SaxElementClose name) -> "Element Close" (SAX.SaxElementTag name attrs) -> "No Content Element" (SAX.SaxCharData charData) -> "Character Data" (SAX.SaxReference reference) -> "Reference" --- End Haskell Code --- The Python code below throws an exception when parsing the same input document. --- Python Code --- from xml.sax import make_parser from xml.sax.handler import ContentHandler def main(): c = ContentHandler() p = make_parser() p.setContentHandler(c) p.parse(open('input.xml')) if __name__ == '__main__': main() -- End Python Code --- Is this a bug in the HaXml SAX parser? Thanks, David