Add function compilation

Functions are compiled in the most naiive way right now. I want to fix
up how scope lookups are done before it becomes too much to update.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/vm/mod.rs

@@ -143,16 +143,16 @@ impl<'p> Vm<'p> {
     fn begin_call(&mut self, caller: ObjRef, args: Vec<ObjRef>) {
         // create stack frame
         let stack_frame = if let Some(user_fun) = std::any::Any::downcast_ref::<UserFunRef>(&caller) {
-            let locals = {
+            let names: Names = {
                 read_obj!(let fun_ref = user_fun);
                 fun_ref.locals()
                     .iter()
                     .zip(args.into_iter())
-                    .map(|((k, _), v)| (*k, v))
+                    .map(|((_, v), arg)| (*v, arg.clone()))
                     .collect()
             };
 
-            Frame::new(locals, FrameKind::User {
+            Frame::new(names, FrameKind::User {
                 last_pc: self.pc(),
                 stack_base: self.stack().len(),
                 fun: user_fun.clone(),