Re: [Haskell-Cafe] Parsing bytestream

15 Nov 2010


      Hi Felipe,


On Tue, Nov 9, 2010 at 3:53 PM, Felipe Almeida Lessa
 wrote:
...
On Tue, Nov 9, 2010 at 8:10 AM, C K Kashyap  wrote:
] I think I can restate my problem like this ---
]
] If I have a list of actions as follows -
]
] import Data.Word
] import Data.Binary.Get
]
] data MyAction = A1 (Get Word8) | A2 (Get Word16)
]
] a = A1 getWord8
] b = A2 getWord16be
]
] listOfActions = [a,b,a]
]
] How can I execute the "listOfActions" inside of a Get Monad and get
] the output as a list?
Do you mean, something like this?
...
import Control.Applicative ((<$>))
data MyAction m = A1 (m Word8) | A2 (m Word16)
a = A1 getWord8
b = A2 getWord16be
listOfActions = [a,b,a]
newtype Id a = Id a
getAction :: MyAction Get -> Get (MyAction Id)
getAction (A1 act) = A1 . Id <$> act
getAction (A2 act) = A2 . Id <$> act
getActions :: [MyAction Get] -> Get [MyAction Id]
getActions = mapM getAction
--
Felipe.
Could you please give a solution for Put as well ... I need to
generate a series of put actions from a list of tuples as follows -

[(100,1),(200,2),500,4)] -> [putWord8 100, putWord16be 200, putWord32be 500]

-- 
Regards,
Kashyap