Yes, the messages! In Haskell, you would get the effect with a higher-level function that can add context, or something like <?> in Parsec, or maybe a custom fu

Yes, the messages! In Haskell, you would get the effect with a higher-level function that can add context, or something like <?> in Parsec, or maybe a custom function that calls catchError. In the continuation-passing style like you get in JS promises, you can do this with .catch(err=>...).