(* This first one does not work ! *)
fun contains(x, []) = false
  | contains(x, x::rest) = true                (* bad! *)
  | contains(x, y::rest) = contains(x, rest);

(* Instead, use the conditional operator *)
fun contains(x, []) = false
  | contains(x, y::rest) = 
        if x = y 
        then true 
        else contains(x, rest);


(* Alternately, we could do it this way... *)
fun contains(x, []) = false
  | contains(x, y::rest) = x = y orelse contains(x, rest);



(* Ex 3.7.5, hasNoRepeats (in class) *)
fun hasNoRepeats([]) =  true
  | hasNoRepeats(x::rest) = 
    if contains(x, rest)  then false else hasNoRepeats(rest);


fun hasNoRepeats([]) =  true
  | hasNoRepeats(x::rest) = not (contains(x, rest)) andalso hasNoRepeats(rest);





(* Ex 3.7.6, isSubsetOf (in class) *)
fun isSubsetOf([], bb) = true
  | isSubSetOf(a::rest, bb) =  if contains(a, bb) then isSubSetOf(rest,bb) else false;



(* Ex 3.7.7, intersection (HW) *)
(* Order doesn't matter, but there should be no repated 
   elements; you may assume the parameters have no 
   repeated elements. *)
fun intersection([], bb) = 
  | intersection(a::rest, bb) = 

(* Ex 3.7.10, numEvens (in class) *)
fun numEvens([]) = 0
  | numEvens(a::rest) = if a mod 2 = 0 then 1 + numEvens(rest) else numEvens(rest);

fun numEvens([]) = 0
  | numEvens(a::rest) = numEvens(rest) + (if a mod 2= 0 then 1 else 0);

fun numEvens([]) = 0
  | numEvens(a::rest) = ((a + 1) mod 2) + numEvens(rest) ;




(* Ex 3.7.11, removeFirst (in class) *)
fun removeFirst(x, []) = []
  | removeFirst(x, y::rest) = if x = y then rest else y::removeFirst(x, rest);




(* Ex 3.7.12, listMin (HW) *)
fun listMin([x])= x
  | listMin(x::rest) =