To parse a whole document, xmlParse file content takes a filename (for generating error reports) and the string content of that file. A parse error causes program failure, with message to stderr.

To parse a whole document, xmlParse' file content takes a filename (for generating error reports) and the string content of that file. Any parse error message is passed back to the caller through the Either type.

To parse just a DTD, dtdParse file content takes a filename (for generating error reports) and the string content of that file. If no DTD was found, you get Nothing rather than an error. However, if a DTD is found but contains errors, the program crashes.

To parse just a DTD, dtdParse' file content takes a filename (for generating error reports) and the string content of that file. If no DTD was found, you get Right Nothing. If a DTD was found but contains errors, you get a Left message.