Thanks for the pointer.

This note in the documentation for that egg looks worrisome [1]: "IMPORTANT: This only works when the code will be run on exactly the same platform as the Scheme compiler ran on. Cross-compilation and compiling to C and compiling that on the target platform is not supported. (You will get an error message when you try to do it anyway)"

Does this mean that cross-compiling for iOS would preclude using this bignum egg ?

[1] http://wiki.call-cc.org/eggref/4/numbers#compiled-code

I have no experience with it personally, so that might indeed be the case. If anyone mentions otherwise on IRC (#chicken on freenode) I will update this accordingly.

I remember some horrible compilation issues with this library while I was trying to get some academic code running - they used the rationals in GMP.