Map.

Monadic bind. p >>= f results in a new parser which behaves as p then, in case of success, applies f to the result.

Applicative.

a <* b parses a into x, parses b and ignores its result, and returns x.

a *> b parses a, then parses b into x, and returns x. The results of a is ignored.

a <|> b tries to parse a, and if a fails without consuming any input, backtracks and tries to parse b, otherwise it fails as a. See try_ to ensure a does not consume anything (but it is best to avoid wrapping large parsers with try_).

a <?> msg behaves like a, but if a fails without consuming any input, it fails with msg instead. Useful as the last choice in a series of <|>: a <|> b <|> c <?> "expected a|b|c".