These are examples C codes of what you can achieve with libnftnl.
Basic functions are:
 * fetch the ruleset from the kernel.
 * update (add/delete) the ruleset.
 * Set-up an event listener environment.
 * Play with nftables sets infraestructure

To compile the examples, run:
 $ gcc -lmnl -lnftnl nft-rule-add.c -o nft-rule-add

You will need the Linux kernel nf_tables.h header:
 * linux/netfilter/nf_tables.h

Then you can run:
 $ sudo ./nft-rule-add ip filter input