let tuesday () = true;;

let abbrev () =
  if tuesday() then
     let x = 2 + 3 in
     x + x
  else
     0
;;

let add_one (x:int) : int = 1 + x;;

let add_two (x:int) : int = add_one (add_one x);;

let add_two' (x:int) : int = 
  let add_one x = 1 + x in
  add_one (add_one x)
;;

let x = 3;;

let add_three (y:int) : int = y + x ;;

let x = 4 ;;

let add_four (y:int) : int = y + x ;;

let add_seven (y:int) : int =
  add_three (add_four y)
;;

let print_17 () =
  print_int (add_seven 10);
  print_newline()
;;

let pair : int * int = (1,2) ;;

let triple : string * int * bool = ("hello", 7 + 3, true) ;;

let pair_of_pairs : char * (string * string) = ('a', ("hello", "goodbye")) ;;

type point = float * float

let distance (p1:point) (p2:point) : float =
  let (x1,y1) = p1 in 
  let (x2,y2) = p2 in
  let square x = x *. x in
  sqrt (square (x2 -. x1) +. square (y2 -. y1))
;;

let p1 = (2.0,3.0);;
let p2 = (0.0,1.0);;
let mydist = distance p1 p2;; 

let slope (p1:point) (p2:point) : float option =
  let (x1,y1) = p1 in 
  let (x2,y2) = p2 in
  let xd = x2 -. x1 in
  if xd != 0.0 then
    Some ((y2 -. y1) /. xd)
  else
    None 
;;

let print_slope (p1:point) (p2:point) : unit = 
  match slope p1 p2 with
    Some s -> print_string ("Slope: " ^ string_of_float s)
  | None -> print_string "Vertical line.\n"
;;

let distance2 (p1:point) (p2:point) : float =
  let square x = x *. x in
  match p1 with
  | (x1,y1) ->  
     match p2 with
     | (x2,y2) ->
        sqrt (square (x2 -. x1) +. square (y2 -. y1))
;;

let distance3 (p1:point) (p2:point) : float =
  let square x = x *. x in
  match (p1, p2) with
  | ((x1,y1), (x2, y2)) ->  
    sqrt (square (x2 -. x1) +. square (y2 -. y1))
;;

let small_prime (n:int) : bool =
  match n with
  | 2 -> true
  | 3 -> true
  | 5 -> true
  | _ -> false
;;

let iffy (b:bool) : int =
  match b with
  | true -> 0
  | false -> 1
;;

type java_pair = (int * int) option

let swap_java_pair (p:java_pair) : java_pair =
  match p with
    | None -> None
    | Some (x,y) -> Some (y,x)

type pair = int * int

let swap_pair (p:pair) : pair =
  let (x,y) = p in (y,x)