[Chicken-users] Importing alien bignums

[John Cowan]

My Q-language egg is coming along nicely, and I've run into an issue with
bignums vs. FFI.  When the numbers egg is installed, Chicken represents
bignums as mpz_t objects from the GMP.  Q has bignums as standard,
and uses the same representation and library.

However, there is not surprisingly no support for bignums in the FFI.
How can I persuade Chicken to treat a c-pointer coming from the FFI as an
(mpz_t *) and consider it to be a Scheme number?  (Obviously this would
only be done if the full-numeric-tower: feature is available.)

Naturally, bignums have to be copied both ways so that the two garbage
collectors don't collide.  

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