Refactor some examples.

examples/repl.rs

@@ -1,34 +1,19 @@
 use rhai::{Engine, RegisterFn, Scope};
-use std::fmt::Display;
 use std::io::{stdin, stdout, Write};
 use std::process::exit;
 
-fn showit<T: Display>(x: &mut T) -> () {
-    println!("{}", x)
-}
-
-fn quit() {
-    exit(0);
-}
-
 pub fn main() {
     let mut engine = Engine::new();
     let mut scope = Scope::new();
 
-    engine.register_fn("print", showit as fn(x: &mut i32) -> ());
-    engine.register_fn("print", showit as fn(x: &mut i64) -> ());
-    engine.register_fn("print", showit as fn(x: &mut u32) -> ());
-    engine.register_fn("print", showit as fn(x: &mut u64) -> ());
-    engine.register_fn("print", showit as fn(x: &mut f32) -> ());
-    engine.register_fn("print", showit as fn(x: &mut f64) -> ());
-    engine.register_fn("print", showit as fn(x: &mut bool) -> ());
-    engine.register_fn("print", showit as fn(x: &mut String) -> ());
-    engine.register_fn("exit", quit);
+    engine.register_fn("exit", || exit(0));
 
     loop {
         print!("> ");
+
         let mut input = String::new();
         stdout().flush().expect("couldn't flush stdout");
+
         if let Err(e) = stdin().read_line(&mut input) {
             println!("input error: {}", e);
         }