open Lang.MiniFun

(* -------------------------------------------------------------------------- *)
(* Identity program *)
let program =
  Function
    (["a"],
     (Variable "a")
    )
;;

Printf.printf "%d\n" (reduce program 1)

(* -------------------------------------------------------------------------- *)
(* Constant program *)
let program =
  Function
    (["a"],
     (Integer 1)
    )
;;

Printf.printf "%d\n" (reduce program 10)

(* -------------------------------------------------------------------------- *)
(* Partial application of function program *)
let program =
  LetIn
    ("f",
     (Function (["x"; "y"], Plus (Variable "x", Variable "y"))),
     (Application (Variable "f", [Integer 3]))
    )
;;

Printf.printf "%d\n" (reduce program 2)

(* -------------------------------------------------------------------------- *)
(* Partial application of function program *)
let program =
  LetFun
    ("f",
     ["x"],
     (Function (["y"], Plus (Variable "x", Variable "y"))),
     (Application (Variable "f", [Integer 3]))
    )
;;

Printf.printf "%d\n" (reduce program 3)

(* -------------------------------------------------------------------------- *)
(* Passing functions to functions program *)
let program =
  LetIn
    ("f",
     (Function (
         ["z"],
         (Function (
             ["y"],
             Function (
               ["x"],
               (IfThenElse (
                   CmpLess (Variable "x", Integer 0),
                   (Application (Variable "y", [Variable "x"])),
                   (Application (Variable "z", [Variable "x"]))
                 )))
           ))
       )),
     (Application
        (
          (Application
             (Variable "f",
              [Function (["x"], Plus (Variable "x", Integer 1))]
             )
          ),
          [Function (["x"], Minus (Variable "x", Integer 1))]
        )
     )
    )
;;

Printf.printf "%d\n" (reduce program (3));
Printf.printf "%d\n" (reduce program (-3))

(* -------------------------------------------------------------------------- *)
(* Recursive function program *)
let program =
  LetFun
    ("f",
     ["x"],
     (IfThenElse (CmpLess (Variable "x", Integer 2),Integer 1, Plus (Variable "x", Application (Variable "f", [Minus (Variable "x", Integer 1)])))),
     (Variable "f")
    )
;;

Printf.printf "%d\n" (reduce program 10)

(* -------------------------------------------------------------------------- *)
(* Scope program *)
let program =
  LetIn
    ("f",
     (LetIn ("a", Integer 1, (Function (["y"], Plus (Variable "y", Variable "a"))))),
     (LetIn ("a", Integer 2, Variable "f"))
    )
;;

Printf.printf "%d\n" (reduce program 4)