(* --- In-class example --- *)
 
 
  datatype icecream = VanillaIC | ChocolateIC | StrawberryIC |
    CookieDoughIC | CricketIC | BananaIC;
 
  datatype syrup = ChocolateS | CaramelS | StrawberryS | HotFudge;
 
  datatype topping = RainbowSprinkles | ChocolateSprinkles 
                 | ChocolateChips | Walnuts | Pecans | Cherry 
                 | WhippedCream | GummyBears | Crickets;
 
  datatype cone = CakeC | SugarC | WaffleC;
 
  datatype donutDough = CakeD | YeastD;
 
  datatype donutFlavor = VanillaD | ChocolateD | BlueberryD | 
                  PumpkinD | AppleCiderD | RedVelvetD ;
 
  datatype frostingFlavor = VanillaF | ChocolateF | MapleF | PeanutButterF;
 
  datatype donutEncasement = Plain | Frosting of frostingFlavor | Glaze | Powder;
 
  datatype pop = RootBeer | Cola | LemonLime;
 
  datatype treat = IcecreamCone of icecream * cone
               | IcecreamSundae of icecream * syrup * topping
               | Donut of donutDough * donutFlavor * donutEncasement
               | Float of pop * icecream;
 
 
  (* --- from the book --- *)
 
 
  datatype number = Int of int | Real of real;
 
  (* interpret the first int as numerator and second 
      as denominator *)
  datatype rational = Fraction of int * int;
 
 
  (* 1.10.1 *)  (* A HW problem; this is just to get you started *)
  datatype book = 
             (* author, title, pages *)
      Novel of string * string * int
            (* title, number of vols *)
    | RefBook of string * int  
            (* author, title, subject, pages *)
    | NonFiction of string * string * string * int
              (* author, title, subject, publisher *)
    | Textbook of string * string * string * string
    ...
 
  datatype libraryItem =
    Book of book
    | Recording of recording
 
 
  (* Simple function examples *)
 
  fun fahrToCel(t) = (t - 32) * 5 div 9;
 
  fun f(x) = 3.0 * x*x - 2.7 * x + 14.4;
 
  fun capitalize(s) =
      str(Char.toUpper(String.sub(s, 0))) ^
      String.substring(s, 1, size(s) - 1);