#![allow(unused_variables,dead_code)]
type Username = String;


enum DBLookup {
    Result { usr: Username, major: String, gpa :f32 },
    PrivacyRequested(Username),
    NoSuchEntry{},
    DatabaseDown(),
}


fn main() -> () {
    let result1: DBLookup = DBLookup::NoSuchEntry{};
    let result2: DBLookup = DBLookup::PrivacyRequested(String::from("ibarland"));
    let result3: DBLookup = DBLookup::Result{usr: String::from("jchase"), major: String::from("CSAT"), gpa: 3.9};
    

    println!( "{}", match &result2 {
                       DBLookup::Result { usr, major, gpa } => &usr,
                       DBLookup::PrivacyRequested(u) => &u,
                       DBLookup::NoSuchEntry{} => "they don't exist",
                       DBLookup::DatabaseDown() => "cannot connect; try later."
                       } );

    println!("hi");
}




// Note: Here are two correct ways to do LinkedLists:


enum LinkedList<T> {
   Empty(),
   Cons{ first: T, rest: Box<LinkedList<T>> }
   }


// OR, rather than a type LinkedList, use `<Option<Box<Cons<T>>`:
//
struct Cons<T> {
   val: T,
   next: Option<Box<Cons<T>>>
   }