(*
 * This file contains an assoc function equivalent to that in alist.ml, but
 * here the definition of assoc is pattern based.
 *)
fun assoc(key, nil) = ("", 0) |
    assoc(key, al::als) =
        if key = #1(al) then al else assoc(key, als);

(*
 * Simple tests of the alist functions.
 *)
val a = [("x",10),("y",20),("z",30)];
#2(assoc("x", a));
#2(assoc("z", a));
#2(assoc("w", a));