XQuery3.0: Higher-Order functions (Functional composition)

	xquery version "3.0";
	declare function local:compose($f1 as function(item()) as item(), $f2 as function(item()) as item())
	as function(item()) as item() {
	function($item) as item() {
	$f2($f1($item))
	}
	};
	(: 5 * x - 2 :)
	let $linearFunction :=
	local:compose(
	function($number) {$number * 5},
	function($number) {$number - 2})
	(: 3 * x^2 - 4 :)
	let $quadraticFunction :=
	local:compose(
	function($number) {$number * $number * 3},
	function($number) {$number - 4})
	return
	<result>
	<test1>{$linearFunction(5)} should equal 5 * 5 - 2 = 23</test1>
	<test2>{$quadraticFunction(4)} should equal 3 * 4^2 - 4 = 44</test2>
	</result>
	(:
	**********************************************
	XQuery output:
	**********************************************
	<result>
	<test1>23 should equal 5 * 5 - 2 = 23</test1>
	<test2>44 should equal 3 * 4^2 - 4 = 44</test2>
	</result>
	:)

view raw gistfile1.xquery hosted with ❤ by GitHub