[Haskell-cafe] Re: Network parsing and parsec

Jan-Willem Maessen jmaessen at alum.mit.edu
Wed Sep 21 13:36:58 EDT 2005

On Sep 20, 2005, at 6:32 PM, Benjamin Franksen wrote:

> On Tuesday 20 September 2005 16:50, John Goerzen wrote:
>> On the flip side, Parsec is really nice.  I wonder how easy it would
>> be to make it parse [Word8] instead of String?
> Isn't Parsec parameterized over the token type?
>> Or even a
>> FastPackedString? (And how easy it would be to get that instead of a
>> String from hGetContents)?
> From the FPS haddock:
> hGetContents :: Handle -> IO FastString
>   Read entire handle contents into a FastString.
> This may or may not do what you want...it's probably not a lazy read.

It seems like there might need to be something like:

hGetContentsLazily :: Handle -> IO [FastString]

which returns file contents in chunks based on our ability to buffer 
the handle.  If we can mmap the handle, we may get a singleton list 
with a giant FastString; if we are using a Socket or a terminal, each 
succeeding string might be the next chunk of available data from the 

I had the impression the internals of getContents from the prelude 
worked a bit like this (in GHC, anyway).

-Jan-Willem Maessen

> Ben
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