I wrote a libxml2 binding in Haskell (http://hackage.haskell.org/package/libxml-sax http://hackage.haskell.org/package/libxml-sax). It was an absolute nightmare

I wrote a libxml2 binding in Haskell (http://hackage.haskell.org/package/libxml-sax http://hackage.haskell.org/package/libxml-sax). It was an absolute nightmare, in part because handling entities safely requires a lot of hoop-jumping (and I'm not even 100% I caught all the places libxml2 does unsafe stuff).