Finance Combinators[S. Peyton Jones and J.M. Eber, ``How to write a financial contract'', in The Fun of Programming, ed Gibbons and de Moor, Palgrave Macmillan 2003]

(zero)	a contract that has no rights
	and no obligations
(one k)	one unit of currency k
c	you immediately acquire contract c
(give c)	to give a contract c to another party;
	like negation
(at t c)	if you acquire contract c before time t,
	it becomes effective at time t
(truncate t c)	contract c ceases to exist after time t
(and c1 c2)	both contracts c1 and c2
(or c1 c2)	your choice of contracts c1 and c2
(cond b c1 c2)	you acquire contract c1
	if the observable b is true,
	else you acquire c2
(scale o c)	multiply contract c by observable o
(when b c)	you must acquire contract c
	when b becomes true
	(but worthless if b can never be true)
(anytime b c)	you may acquire contract c
	any time b becomes true
(until b c)	is like contract c but must be abandoned
	when b becomes true