building and analysing C structs with Storable

[Henning Thielemann]

On Sat, 13 Oct 2007, Adam Langley wrote:

> On 10/13/07, Henning Thielemann <lemming at henning-thielemann.de> wrote:
>> Are there analogons to ByteString's Put and Get Monads to construct and
>> disect binary data in a C struct for exchange with a C program?
>
> The memory layout of structs depends on the ABI of system. You can
> take a guess and write code in the Get and Put monads. Your guess will
> probably work pretty well within a single architecture (e.g. x86 or
> x86-64).
>
> However, the portable way to do this is to get the information from
> the C compiler, which is the approach that c2hs[1] and friends use. I
> would recommend this unless there's some good reason to think
> otherwise. (see [2] for the exact hook)
>
> [1] http://www.cse.unsw.edu.au/~chak/haskell/c2hs/
> [2] http://www.cse.unsw.edu.au/~chak/haskell/c2hs/docu/c2hs-2.html#ss2.8

I do not quite see the need for an extra tool. I thought it must be 
possible to ship a Haskell compiler with modules that depend on the 
system's C compiler, just like the modules that are implemented 
differently for Windows and Unix. Such modules could provide the 
functionality to create and inspect C structs for exchange with system 
libraries.