[Haskell-cafe] Abstraction leak
andrewcoppin at btinternet.com
Fri Jun 29 18:14:39 EDT 2007
David Roundy wrote:
> On Fri, Jun 29, 2007 at 07:39:28PM +0100, Andrew Coppin wrote:
>> Now I have a problem. It's easy enough to pass the entire data stream
>> through an RLE decoder and feed that to the Huffman table deserialize
>> function, and it will give be back the table. But I now have *no clue*
>> where the table ends in the original stream!
> Sounds to me like you want a parsing monad. Generally, when you want
> state, you want a monad, and the field of parsing monads is pretty mature.
> You can either write up a monad of your own, or use one of the existing
> ones (parsec, frisby, read).
Perhaps. But how do you run a parser on top of another parser? More
importantly, how do you stack several parsers one on top of the other,
get the top-most one to return the thing it parsed, and then make a
completely different stack of parsers process the remainder?
I'm sure it can be done, but... I'm having trouble wrapping my mind
around that at this time of night... :-S
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