use "eg.sml";

(* -------------------------------------- *)
val lf1 = Fork(EmptyTree,1,EmptyTree)
and lf2 = Fork(EmptyTree,2,EmptyTree)
val t   = Fork(lf1, 3, lf2);

height t > 0;
t <> EmptyTree;

(* --------------------------------------- *)
val L1 = [1,2,3]
and L2 = [4,5,6]
and L3 = [7,8,9];

append(append L1 L2) L3;
append L1 (append L2 L3);

(* --------------------------------------- *)
map (op +) (zip L1 L2);
zipWith (curry(op +)) L1 L2;