To compile `libfactorial.dylib` on OS X:

    $ gcc -dynamiclib -undefined suppress -flat_namespace factorial.c -o libfactorial.dylib

To compile `libfactorial.so` on Linux/Solaris/etc.:

    $ gcc -shared -fpic factorial.c -o libfactorial.so

To run the example:

    $ node factorial.js 35
    Your output: 6399018521010896896