[Haskell-cafe] Parsec, updateState, and failure
andrewcoppin at btinternet.com
Sat May 31 10:39:45 EDT 2008
Dimitry Golubovsky wrote:
> 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.
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