[plt-scheme] lex problem

Stephen Bloch wrote:
> I'm trying to teach myself to use the scanner and parser tools in time 
> to provide my students a parser for a C-like language so they can 
> write an interpreter for it.
>
> I'm calling
> (lexer (some-ws (get-token input-port))
>          ((eof) 'eof)
>          ...
>          (#\+ (token-plus-operator))
>          ...
>          ((concatenation #\" (repetition 0 +inf.0 (complement #\")) #\")
>           (token-str-lit-token (chop-fl lexeme)))
>          )
>
> So this should recognize anything that starts with a quotation mark, 
> ends with a quotation mark, and doesn't contain any other quotation 
> marks, as a "str-lit-token".
>
> I call the lexer on the input "\"hello\" + \"there\""
> and it gives me back a single str-lit-token with value "hello\" + 
> \"there"
> rather than (as I expected) a str-lit-token, a plus-operator, and 
> another str-lit-token.
>
> What gives?
>

Sort of a wild guess but does this work instead?

replace (complement #\") with

(intersection (complement #\") any-char)