Cannot make recover_with(via_parser(…)) work

[soywod]

Sorry if the question sounds stupid, but I cannot figure out how the recover_with and via_parser work (using alpha.6). I have the following:

let parser =                                                                          
    just::<_, _, extra::Err<Rich<char>>>("abc").recover_with(via_parser(just("abd")));
assert_eq!(parser.parse("abd").into_result().unwrap(), "abd");                        

which outputs:

called `Result::unwrap()` on an `Err` value: [found 'd' at 2..3 expected ''c'']

I naively expect abc not being parsed to be recovered by abd, what am I missing?

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To give more context, I try to parse either a parser 1 or a parser 2, and both contain similar keywords. Knowing that chumsky is a PEG, a choice((…)) does not work as the beginning of the parser 1 can be partially parsed by the parser 2 and vice versa, which leads to parsing errors. Is error recovery the right approach for such issue?

[zesterer]

The result here is both expected and correct: parser recovery doesn't mean that the error in the first branch (just("abc")) gets swallowed, it just means that an error gets emitted and then parsing continues, using the recovery strategy to 'fill the whole', as it were.

If you check out the docs for ParseResult, you'll see that it's possible for a parser to both produce a valid output and emit errors at the same time. This is what is happening here. recover_with(via_parser(...)) should only be used to recover from errors.

If both patterns are considered valid syntax, then choice/or are the thing to use (both do the same thing internally).