gistfile1.txt

$ rustc --crate-type dylib rusty.rs
$ python rusty.py
5

rusty.py

from cffi import FFI
ffi = FFI()
ffi.cdef("""
    int rusty_sum(int x, int y);
""")
rusty_lib = ffi.dlopen('librusty.so')
result = rusty_lib.rusty_sum(2, 3)
print result

rusty.rs

#[no_mangle]
pub extern fn rusty_sum(x: int, y: int) -> int {
    x + y
}