Working with Datatypes

(* Create a binary tree, test whether an element occurs in the tree, and insert an element *)

val mytree = I(50,I(25,L(10),L(40)),I(75,L(60),L(90)));

fun member (i, NULL) = false |

member (i, L(j)) = (i = j) |

member (i, I(j, ls, rs)) =

if i = j then true

else if i < j then member (i, ls)

else member (i, rs);