[Haskell-cafe] bitSize

Andrew Coppin andrewcoppin at btinternet.com
Mon Aug 29 10:32:29 CEST 2011


On 29/08/2011 09:00 AM, Brandon Allbery wrote:
> On Mon, Aug 29, 2011 at 03:40, Andrew Coppin
> <andrewcoppin at btinternet.com <mailto:andrewcoppin at btinternet.com>> wrote:
>
>             I meant if you're trying to *implement* serialisation. The Bits
>             class allows you to access bits one by one, but surely you'd
>         want
>             some way to know how many bits you need to keep?
>
>         I think that falls into the realm of protocol design; if you're
>         doing it
>         in your program at runtime, you're probably doing it wrong.
>           (The fixed
>         size version makes sense for marshaling; it's *dynamic* sizes
>         that need
>         to be thought out beforehand.)
>
>
>     If you're doing, say, cryptography, then thousand-bit random
>     integers that need to be serialised are fairly common...
>
>
> Sure, and there are encodings that let you do this without needing
> bitSize (BER).  You need a word count, but that's usually part of the
> structure holding the integer.

OK. But since there's no way of getting a byte count for an Integer 
either...



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