What big external dependencies do you need for a parser? `String -> Result<Email, Error>` shouldn't need any other parameters? But you should ideally still ha

What big external dependencies do you need for a parser? `String -> Result<Email, Error>` shouldn't need any other parameters? But you should ideally still have some simple field-wise constructor (whatever that means, it's language-dependent) anyways, the function from String would delegate to that after either extracting all of the necessary components or returning/throwing an error.