Re: [Haskell-cafe] Binary parser combinators and pretty printing
On 13.09 23:31, Tomasz Zielonka wrote: How about all these points together?: a) Simple monadic interface I think I already have this - minus packaging and documentation. b) Using better combinators This is lacking. c) Using TH to generate code for the simple cases I have TH for generating code, but that is not yet general purpose (the code comes from SerTH). d) Using type-classes As most real-world protocols will need customization I cannot see much improvement here. Keeping the types of the serialized data explicit makes sense. Otherwise changing an innocent Haskell data declaration would cause on-wire data mismatch rather than compile-time type errors. I've played with such frameworks a couple of times and I feel it's time to make a library useful for others. If you're interested, we could cooperate. I would be interested in cooperation and getting an usefull library released. Currently my parsers just use [FastString] (thus support lazy IO), peek and poke. - Einar Karttunen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Binary parser combinators and pretty printing
Hello Einar, Tuesday, September 13, 2005, 7:03:00 PM, you wrote: EK data Packet = Packet Word32 Word32 Word32 [FastString] well. you can see my own BinaryStream package at http://freearc.narod.ru class BinaryData a where read :: ... write :: ... instance BinaryData Word32 where read = ... write = ... instance BinaryData FastString where read = ... write = ... instance (BinaryData a, BinaryData b, BinaryData c, BinaryData d) = BinaryData (a,b,c,d) where read = ... write = ... instance (BinaryData a) = BinaryData [a] where read = ... write = ... EK 1) Simple monadic interface EK getPacket = do mid - getWord32BE EKsid - getWord32BE EKrid - getWord32BE EKnmsg- getWord32BE EKvars- replicateM (fromIntegral nmsg) (getWord32BE = getBytes) EKreturn $ Packet mid sid rid nmsg vars turns into: (a,b,c,d) - read return $ Packet a b c d EK Maybe even the tuple could be eliminated by using a little of TH. it may be eliminated even without TH! :+: and :*: should work, although i don't tried this -- Best regards, Bulatmailto:[EMAIL PROTECTED] ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Binary parser combinators and pretty printing
On 15.09 21:53, Bulat Ziganshin wrote: EK data Packet = Packet Word32 Word32 Word32 [FastString] well. you can see my own BinaryStream package at http://freearc.narod.ru class BinaryData a where read :: ... write :: ... I don't think this is a very good solution. Keeping the on-wire datatypes explicit makes sense to me. Also things like endianess will need to be taken into account. If the encoding is derived automatically then changing the Haskell datatype will change the on-wire representation. This is not wanted when interfacing with external protocols. For typeclasses I would rather have: getWord32BE :: Num a = MyMonad a than get :: MyClass a = MyMonad a Note the difference between the Haskell type determining the on-wire type and it being explicit. I already have working TH code for the case where I want to derive automatic binary serialization for Haskell datatypes (SerTH). EK Maybe even the tuple could be eliminated by using a little of TH. it may be eliminated even without TH! :+: and :*: should work, although i don't tried this I don't know how generics work in newer versions of GHC, but it may be worth investigating. - Einar Karttunen ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Binary parser combinators and pretty printing
Einar Karttunen ekarttun@cs.helsinki.fi writes: I am trying to figure out the best interface to binary parser and pretty printing combinators for network protocols. 2) Using better combinators packet = w32be w32be w32be lengthPrefixList w32be (lengthPrefixList w32be bytes) Has anyone used combinators like this before and how did it work? Yes, the nhc98 Binary library has a combinator, in very much the style you outline. It is only used in pure code, but it permits some very concise descriptions of the binary layout. The library is described here: ftp://ftp.cs.york.ac.uk/pub/malcolm/ismm98.html but unfortunately that paper has only the tiniest examples of the usage of . However, in my experience the style worked well and was pleasant to use. Regards, Malcolm ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
