Re: [Haskell-cafe] Re: Data.Binary Endianness

2007-09-11 Thread Sven Panne 
On Monday 10 September 2007 21:02, apfelmus wrote:
 [...]
class Put a endian where
  put :: endian - a - Put
 [...]
 Oh, and the 8,16,32 and 64 are good candidates for phantom
 type/associated data types, too.

I think that using any non-H98 feature like MPTC or associated data types for 
such a generally useful and basic package would be a *big* mistake.  Let's 
follow the KISS principle here. Everybody is free to make a nicer, but 
non-portable wrapper...

Cheers,
   S.
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Re: [Haskell-cafe] Re: Data.Binary Endianness

2007-09-11 Thread Lutz Donnerhacke 
* apfelmus wrote:
 It's not that related, but I just got struck by an obvious idea, namely
 to put the endianness in an extra parameter

data Endianness = Little | Big | Host
putInt32 :: Endianness - Int - Put

Please add the endianess to the state of the monad Put.
  setendianess :: Endianness - Put

And for convinience please add the Network constructor to the type
Endianness. ,-)
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[Haskell-cafe] Re: Data.Binary Endianness

2007-09-10 Thread apfelmus 

Sven Panne wrote:
 So what I was asking for is:


   getInt32be, putIEEEFloatLe, getIEEEDoubleHost, ...

Type classes might be used to get a slightly smaller API, but I am unsure 
about the performance impact and how much this would really buy us in terms 
of the ease of use of the API.


It's not that related, but I just got struck by an obvious idea, namely 
to put the endianness in an extra parameter


  data Endianness = Little | Big | Host
  putInt32 :: Endianness - Int - Put

in order to avoid three functions for every data type. I don't know 
whether this makes performance a bit worse, but if it does, phantom 
types or similar are an option to encode endianness, too.


  data LE = LE
  data BE = BE
  data Host = Host

  class Put a endian where
put :: endian - a - Put

  instance Put Int32 LE where ...
  instance Put Int32 BE where ...
  instance Put Int32 Host where ...

Oh, and the 8,16,32 and 64 are good candidates for phantom 
type/associated data types, too.


Regards,
apfelmus

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