By "know" would you say for example you can use well function pointers in c and other advanced topics in all the languages you list? for example can you tell me what this does?

   int add1To2(int (*adder)(int, int)) {
    return (*adder)(1,2);
   }

Im just asking because I think theres a lot to be gained by actually digging deep into the internals of languages you already work with or use. I'm doing this with ruby right now reading through Matzs source. Anyways, Id suggest ruby since its my personal favorite :)