extern crate rustyline;

use rustyline::completion::FilenameCompleter;
use rustyline::error::ReadlineError;
use rustyline::Editor;

fn main() {
    let c = FilenameCompleter::new();
    let mut rl = Editor::new();
    rl.set_completer(Some(&c));
    if let Err(_) = rl.load_history("history.txt") {
        println!("No previous history.");
    }
    loop {
        let readline = rl.readline("\x1b[1m>> \x1b[0m");
        match readline {
            Ok(line) => {
                rl.add_history_entry(&line);
                println!("Line: {}", line);
            },
            Err(ReadlineError::Interrupted) => {
                println!("CTRL-C");
                break
            },
            Err(ReadlineError::Eof) => {
                println!("CTRL-D");
                break
            },
            Err(err) => {
                println!("Error: {:?}", err);
                break
            }
        }
    }
    rl.save_history("history.txt").unwrap();
}

extern crate rustyline;

use rustyline::completion::FilenameCompleter;
use rustyline::error::ReadlineError;
use rustyline::Editor;

fn main() {
    let c = FilenameCompleter::new();
    let mut rl = Editor::new();
    rl.set_completer(Some(&c));
    if let Err(_) = rl.load_history("history.txt") {
        println!("No previous history.");
    }
    loop {
        let readline = rl.readline(">> ");
        match readline {
            Ok(line) => {
                rl.add_history_entry(&line);
                println!("Line: {}", line);
            },
            Err(ReadlineError::Interrupted) => {
                println!("CTRL-C");
                break
            },
            Err(ReadlineError::Eof) => {
                println!("CTRL-D");
                break
            },
            Err(err) => {
                println!("Error: {:?}", err);
                break
            }
        }
    }
    rl.save_history("history.txt").unwrap();
}

--- 
+++ 
@@ -12,7 +12,7 @@
         println!("No previous history.");
     }
     loop {
-        let readline = rl.readline(">> ");
+        let readline = rl.readline("\x1b[1m>> \x1b[0m");
         match readline {
             Ok(line) => {
                 rl.add_history_entry(&line);
Make the prompt bold with ANSI escape code.
