Maciej Podgurski <[EMAIL PROTECTED]> wrote: > Hi, > > I'm currently writing a parser using the Parsec library. What I want > is to store the order of each subparser called in a user state. So > every single parser will be marked with a label that is stored in a > special treelike structure when the parser is run. > > My problem is to return the last state of this structure when a parse > error occurred. This information shall be used to display a kind of > stack trace showing the order of the parser calls for debug purposes. > Any ideas how to achieve this? > Write the parser in a way that can never, ever fail, and return the parse error as part of your tree. That is, write a wrapper that puts optionMaybe's around every parser you call and records label, position and everything, and maybe go ahead and roll your own monad inside of ParsecT
PS: don't try to influence the parsing based on state, if you don't feel like despairing. Messy cans of worms lay ahead. -- (c) this sig last receiving data processing entity. Inspect headers for past copyright information. All rights reserved. Unauthorised copying, hiring, renting, public performance and/or broadcasting of this signature prohibited. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe