(* a collection of ML functions
*   demonstrating some of the concepts in Chapter 7 *)


fun reverse nil = nil
|   reverse (first :: rest) = reverse rest @ [first];

fun sumList nil = 0
|   sumList ( first :: rest ) = first + sumList rest;


fun hw _ = print "Hello World!\n";


fun prlst(nil) = ()
|  prlst(x::xs) = 
    ( print(Int.toString(x)^ ","); 
      prlst(xs)
      );

val myList = [12,3,5,6,9,~4];

val aList = reverse myList ;

print( " here is the original list \n");
prlst myList;
print("\n");

print(" here is the list reversed \n");

prlst aList;
print("\n");

print( " The sum of the values in the list = ");
print ( Int.toString (sumList myList));
print("\n");

hw myList;