Brian Hulley wrote:

Hi, In the Haskell98 report at http://haskell.org/onlinereport/lexemes.html section 2.2 has the rule:

whitechar -> newline | vertab | space | tab | uniWhite

Does anyone know what a vertical tab is supposed to do? Is there any reason to allow them as whitespace? (Does anyone in the universe actually use them?)

To rephrase my question, what is a Haskell lexer/parser supposed to do when it encounters a vertical tab? The description of the layout rule in the report does not specify what a vertical tab means. If no-one knows the answer, perhaps the rule should be changed to: whitechar -> newline | space | tab | uniWhite and a vertical tab's could just be treated as illegal characters. Regards, Brian. -- Logic empowers us and Love gives us purpose. Yet still phantoms restless for eras long past, congealed in the present in unthought forms, strive mightily unseen to destroy us. http://www.metamilk.com