Handle to haskell data

[Manuel M T Chakravarty]

Fergus Henderson <fjh at cs.mu.oz.au> wrote,

> On 30-Nov-2003, David Waern <davve at dtek.chalmers.se> wrote:
> > 
> > Hi. I want to know if it is possible via FFI and GHC to allocate
> > haskell data structures and return some kind of handle to their internal
> > representation in the haskell runtime to another language that calls
> > haskell code (c/c++).
> 
> I haven't tried it myself, but I think the answer is yes:
> use the StablePtr type, which in C is the HsStablePtr typedef in "HsFFI.h".

Yes, that is exactly what StablePtrs are meant for.  See
also the description of the various pointer types at

  http://www.reid-consulting-uk.ltd.uk/docs/ffi-Common_Problems.html

Manuel