(* Important: For submission, this file must be named Main.ml
 *
 * To build:
 *
 * ocamlbuild -use-ocamlfind -pkg compsci631 -pkg ppx_test Main.d.byte
 *
 * This produces an executable called ./Main.d.byte, which runs all the
 * test cases in the file.
 *
 * By default, OCaml does not display stack traces when an exception occurs.
 * To enable stack traces, run:
 *
 * OCAMLRUNPARAM=b ./Main.d.byte
 *)

(* These are some handy functions from class. *)
let rec map (f : 'a -> 'b) (alist : 'a list) : 'b list = match alist with
| [] -> []
| h :: t -> f h :: map f t

let rec filter (f : 'a -> bool) (alist : 'a list) : 'a list  = match alist with
  | [] -> []
  | h :: t -> if f h then  h :: filter f t else filter f t

let rec length (alist : 'a list) : int = match alist with
| [] -> 0
| _ :: tl -> 1 + length(tl)

(* Fill in the functions below. Do not change their types. *)
let rec map2 (f : 'a -> 'b -> 'c) (alist1 : 'a list)
  (alist2 : 'b list) : 'c list =
  failwith "not implemented"

let rec zip (alist1 : 'a list) (alist2 : 'b list) : ('a * 'b) list  =
  failwith "not implemented"

let rec flatten (alist : 'a list list) : 'a list =
  failwith "not implemented"

let rec flatten3 (alist : 'a list list list) : 'a list =
  failwith "not implemented"

let rec build_list (len : int) (f : int -> 'a) : 'a list =
  failwith "not implemented"

let rec map_list (f : 'a -> 'b list) (alist : 'a list) : 'b list =
  failwith "not implemented"

let rec partition (f : 'a -> bool) (alist : 'a list) : 'a list * 'a list =
  failwith "not implemented"

let rec merge (less_than : 'a -> 'a -> bool) (alist1 : 'a list)
  (alist2 : 'a list) : 'a list = failwith "not implemented"

let rec sort (less_than : 'a -> 'a -> bool) (alist : 'a list) : 'a list  =
  failwith "not implemented"

let%TEST "unsurprisingly, addition works correctly" = 1 + 2 = 3

(* Runs all tests declared with let%TEST. This must be the last line
   in the file. *)
let _ = Testing.run_tests ()