The ListSetFn functor provides a sorted-list implementation of the
ORD_SET signature parameterized over the element type.
This implementation is light weight and fast for small sets, but
for larger applications, it is recommended that one use the
RedBlackSetFn functor instead.
Synopsis
functor ListSetFn (K : ORD_KEY) :> ORD_SET where type Key.ord_key = K.ord_key