Re: [Haskell-cafe] Parsec, updateState, and failure

Dimitry Golubovsky wrote:

Hi,

If a parser which updated user state fails, will such update be reverted?

Without actually checking, I would strongly suspect that yes, if a parser fails, all its state modifications are thrown away. (This is usually what you would want...)

Is there any bracket- or try-catch-finally-like mechanism for Parsec?

I don't think so. If you find yourself wanting to parse data differently depending on stuff you've already seen, you might find it easier to run a 2-pass parser of some kind.