(* CIS 120 Lecture 3.  Demonstrates basic list operations. *)

;; open Assert 

(* Collection of songs by Lady Gaga. *)

let gaga_songs : string list = [ "Bad Romance"; "Alejandro"; "Monster"; "Speechless"; "Dance in the Dark"; "Telephone"; 
									 "So Happy I Could Die"; "Teeth"; "Just Dance"; "Love Game"; "Paparazzi";
									 "Beautiful, Dirty, Rich"; "Eh, Eh (Nothing Else I Can Say)";
									 "Poker Face"; "The Fame"; "Money Honey"; "Again Again"; "Boys Boys Boys";
									 "Brown Eyes"; "Summerboy" ]

(* Some sample playlists *)

let pl1 : string list = ["Bad Romance" ; "Nightswimming" ; "Telephone" ; "Everybody Hurts" ]	
let pl2 : string list = [ "Losing My Religion"; "Man on the Moon"; "Belong" ] 
let pl3 : string list = []   (* a playlist with no songs. *)
let pl4 : string list = [
  "Bad Romance"; "Goldberg Variations"; "Nightswimming"; "Summerboy"; "Telephone"; "Everybody Hurts";
  "Bach's Prelude 19, A Major"; "Bach's Invention 13"; "Again Again"; 
]

(* Number of songs *)

let rec number_of_songs (pl : string list) : int = 
	begin match pl with 
		| [] -> 0
		| song :: pl1 -> 1 + number_of_songs pl1
	end		
		

let test () : bool =
  (number_of_songs pl1) = 4
;; run_test "number_of_songs pl1" test

let test () : bool =
  (number_of_songs pl2) = 3
;; run_test "number_of_songs pl2" test

let test () : bool =
  (number_of_songs pl3) = 0
;; run_test "number_of_songs pl3" test

let test () : bool =
  (number_of_songs gaga_songs) = 20
;; run_test "number_of_songs gaga_songs" test


(* Contains *)

let rec contains (pl : string list) (song : string) : bool =
	begin match pl with
		| [] -> false
		| song1 :: pl1 -> if song1 = song then true else contains pl1 song
	end		 
	


let test () : bool =
  (contains pl1 "Telephone") = true
;; run_test "contains pl1 Telephone" test

let test () : bool =
  (contains pl2 "Telephone") = false
;; run_test "contains pl2 Telephone" test

let test () : bool =
  (contains pl3 "Telephone") = false
;; run_test "contains pl3 Telephone" test

let test () : bool =
  (contains gaga_songs "Telephone") = true
;; run_test "contains gaga_songs Telephone"	 test

			
(* number of gaga_songs *)

let rec number_of_gaga_songs (pl : string list) : int = 
	failwith "number_of_gaga_songs: unimplemented"
	

let test () : bool =
  (number_of_gaga_songs pl1) = 2
;; run_test "number_of_gaga_songs pl1" test

let test () : bool =
  (number_of_gaga_songs pl2) = 0
;; run_test "number_of_gaga_songs pl2" test

let test () : bool =
  (number_of_gaga_songs pl3) = 0
;; run_test "number_of_gaga_songs pl3" test

	
(* all_gaga_songs *)

let rec all_gaga_songs (pl : string list) : string list = 
	failwith "all_gaga_songs: unimplemented"
	
let test () : bool =
  (all_gaga_songs pl1) = [ "Bad Romance"; "Telephone" ]
;; run_test "all_gaga_songs pl1" test

let test () : bool =
  (all_gaga_songs pl2) = [] 
;; run_test "all_gaga_songs pl2" test

let test () : bool =
  (all_gaga_songs pl3) = [] 
;; run_test "all_gaga_songs pl3" test


;; print_endline "gaga.ml: end of file."