MkOptionElt functorfunctor MkOptionElt (structure Elt : 
	ELEMENT) :
	ELEMENT
	where type t = Elt.t option =
OptionElt Cost Specification| Work | Span | |
| equal $(A, B)$ | \[O(1)\] | \[O(1)\] | 
| compare $(A, B)$ | \[O(1)\] | \[O(1)\] | 
| hash $A$ | \[O(|A|)\] | \[O(|A|)\] | 
| toString $A$ | \[O(|A|)\] | \[O(|A|)\] |