On Fri, Apr 3, 2009 at 8:17 PM, Kannan Goundan
I'm writing a parser with Parsec. In the input language, elements of a sequence are separated by commas:
[1, 2, 3]
However, instead of a comma, you can also use an EOL:
[1, 2 3]
Anywhere else, EOL is considered ignorable whitespace. So it's not as simple as just making EOL a token and looking for (comma | eol).
Untested, but hopefully enough so you get an idea of where to start:
-- End of line parser. Consumes the carriage return, if present. eol :: Parser () eol = eof <|> char '\n'
-- list-element separator. listSep :: Parser () listSep = eol <|> (char ',' >> spaces)
-- list parser. The list may be empty - denoted by "[]" myListOf :: Parser a -> Parser [a] myListOf p = char '[' >> sepBy p listSep >>= \vals -> char ']' >> return vals
This would probably be better off with a custom version of the 'spaces' parser that didn't parse newlines. Antoine