On Wed, Apr 20, 2011 at 1:03 PM, Sergey Mironov <ier...@gmail.com> wrote: > Hello cafe. > > Haskell wiki told me about continuation-based parser > Data.Binary.IncrementalGet [1] from binary-strict package. I found the > idea very useful and tried to use it. Original library by Lennart > Kolmodin raises some questions. The lib's main data structures are: >
Lennart Kolmodin has a branch of Binary with incremental get which supports lookAhead: https://github.com/kolmodin/binary/tree/cps I don't have performance measurements, but if you look-ahead too far it obviously isn't good for memory consumption. Antoine > data IResult a = IFailed S String > | IFinished S a > | IPartial (B.ByteString -> IResult a) > > newtype Get r a = Get { unGet :: S -> (a -> S -> IResult r) -> IResult r } > > instance Monad (Get r) where > return a = Get (\s -> \k -> k a s) > m >>= k = Get (\s -> \cont -> unGet m s (\a -> \s' -> unGet (k a) s' cont)) > fail err = Get (\s -> const $ IFailed s err) > > Here, "S" is parser's state. It works well, but currently doesn't > support lookAhead. I tried to add such function and gave up to do it > having current implementation, but write simpler one instead. Please > see IncrementalGet2.hs (link [2] below). Remake is briefly tested, has > no ghc-specific optimizations, but allows user to peek data from > stream. > > What bothering me is the fact that I could actually miss idea (or part > of idea) of the original. If it is so, please let me know :) For > example, what is the point of using separate result type r in original > Get r a? > > [1] - Original IncrementalGet lib. > > http://www.haskell.org/haskellwiki/DealingWithBinaryData#Incremental_parsing > [2] - Main file of remake > > https://github.com/ierton/binary-incremental-get2/blob/a9f9afaa0cbc0435a8acea338a31aafaef53fb6e/src/Data/Binary/IncrementalGet2.hs > [3] - whole github project > https://github.com/ierton/binary-incremental-get2 > -- > Sergey > > sorry for weak English > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
