lesson-plan.md

• Hello, World Example:

  • Explain:
    • fn declaration
    • println is a macro
  • Format strings in println!
    • println("Hello, {}!", world);
    • also show {:?}
  • Move "world" into a local variable so we can change it
    • let name = "fellow Rustaceans"; println("Hello, {}!", name);
  • Abstract into a helper fn
    • fn greet(name: String) { println("Hello, {}!", name); }
    • What goes wrong?
      • Explain format!, show how you can use same helpers
      • Explain push_str and mutable local variables
        • let mut name = format!("fellow "); name.push_str("Rustacean");
  • Call helper fn twice
    • What goes wrong now?
  • Timing notes: ~30 minutes from start to here

• Borrowing Example (~5 min):

  • Show that helper(&name) compiles
  • Show that name.push_str does not
  • Create rustify(name: &mut String) that appends some text
    • Show that I have to modify name to be let mut
  • Show that I can do let p = &name; helper(p);
  • Show that I can do let q = p; helper(p); helper(q);
  • Show that mutable references work differently:
    • { let m = &mut name; rustify(m); } is ok
    • { let m = &mut name; let n = m; rustify(m); } is not
    • { let m = &mut name; let n = m; rustify(n); } is OK again
  • Remove braces. Explain that you cannot have a mutable and immutable reference in scope at the same time. Explain that, for the moment, compiler does not consider that m is not used after the call to rustify, though we are considering changing that rule.

• Timing

  • Intro: ~5 min
  • Hello world: ~5 min (10)
  • Ownership slides: ~10 min (20)
  • Ownership example: ~10 min (30)
  • 3:58 - 4:03 (basic borrow slides: 5min)
  • Borrowing: