(* Code for Lecture 1 *)
(* Brigitte Pientka *)
(* Code for Lecture 1: Evaluation and Typing *)

(* Integers *)
~1 : int; (* NOT -1 *)
4 : int;
~3+2 : int;
5 div 2 : int;

(* Reals *)
3.14 : real;
5.0 / 2.0 : real; (* NOT 5 / 2 *)

(* Type errors
- 5 div 3.0;
stdIn:1.1-1.10 Error: operator and operand don't agree [literal]
  operator domain: int * int
  operand:         int * real
  in expression:
    5 div 3.0
- 5.0 div 3;
stdIn:1.1-1.10 Error: operator and operand don't agree [literal]
  operator domain: real * real
  operand:         real * int
  in expression:
    5.0 div 3
stdIn:1.5-1.8 Error: overloaded variable not defined at type
  symbol: div
  type: real

- 5/3;
stdIn:1.1-1.4 Error: operator and operand don't agree [literal]
  operator domain: real * real
  operand:         int * int
  in expression:
    5 / 3

- 5.0 / 3;
stdIn:1.1-1.8 Error: operator and operand don't agree [literal]
  operator domain: real * real
  operand:         real * int
  in expression:
    5.0 / 3
*)  


(* Booleans *)
true : bool;
false : bool;

if 0 = 0 then 1.0 else 2.0 : real;
if true then 4.0 else 1.0/0.0: real;

(* Type error

- if 0 = 0 then 1.0 else 5 ;
stdIn:1.1-1.25 Error: types of if branches do not agree [literal]
  then branch: real
  else branch: int
  in expression:
    if 0 = 0 then 1.0 else 5

*)


(* Typing and Evaluation *)
(* Some ill-typed expressions *)
(*
2.0 + 1;
if true then 1 else 2.0;
true + 0;
*)

(* Some well-typed expressions without a value *)
(* 
1 div 0;
if 1 div 0 = 0 then true else false;
if false then 4 else 1 div 0;
*)