Type mismatch when using sep_by

[ghost]

Not sure if this is a bug, but it seems like it should work. This code fails to compile:

extern crate combine;
use combine::{digit, letter, sep_by, token, Parser, ParserExt};

fn main() {
    let p = sep_by::<Vec<_>, _, _>(digit(), token(','));
    let result = letter().or(p).parse("1,2,3");
}

With this error:

type mismatch resolving `<&str as combine::primitives::Stream>::Item == collections::vec::Vec<char>`:
 expected char,
    found struct `collections::vec::Vec` [E0271]
src/main.rs:6     let result = letter().or(p).parse("1,2,3");

However, this works just fine:

extern crate combine;
use combine::{digit, letter, token, Parser, ParserExt};

fn main() {
    let result = letter().or(digit()).parse("1,2,3");
}

[Marwes]

In this case the error message is a bit confusing but the issue is that letter() outputs a char while sep_by outputs a Vec and or requires that both parsers outputs the same type. I am not sure what you want to output in this case but this thread about an expression parser might help as well #54

[ghost]

Thanks for the reply. Ultimately, what I'm trying to do is parse a string consisting of letters with optional arguments lists, like this: ABA(1, 2)C(3)DE(4, 5, 6)C. Reading over the thread you linked, it looks like I'll want to make an enum to represent both options. Thanks!