Also it is possible to start multiple Neco schedulers in different threads, there’s an example in the readme.
your library looks well written and clean. thanks for sharing.
if anyone else wants to go coroutine spelunking, these were interesting to me:
https://github.com/higan-emu/libco/tree/master
https://github.com/Tencent/libco
https://github.com/hnes/libaco
https://kernel.googlesource.com/pub/scm/virt/kvm/qemu-kvm/+/...
https://tia.mat.br/posts/2012/09/29/asynchronous_i_o_in_c_wi...
https://www.cs.uml.edu/~bill/cs516/context_paper_rse-pmt.pdf