diff --git a/js/object/api.html b/js/object/api.html
index 197939e0c..b00142899 100644
--- a/js/object/api.html
+++ b/js/object/api.html
@@ -137,48 +137,6 @@ <h1>Exports</h1>
 				</span>
 			</div>
 		</div>
-		<ul>
-			<li class="object" jsapi:id="Array">
-				<div class="name">Array</div>
-				<div class="label">has properties:</div>
-				<ul>
-					<li class="function">
-						<div class="name">choose</div>
-						<span>
-							Converts an array into a single element. First applies the given Filter, if one is given: the Filter
-							should be a filter that only accepts zero or one element of the array.
-						</span>
-						<div class="arguments">
-							<div class="label">Arguments</div>
-							<ol>
-								<li class="value">
-									<span class="type">Array</span>
-									<span>An array.</span>
-								</li>
-								<li class="value">
-									<span class="type">Filter</span>
-									<span>(optional) A Filter that is used to preprocess the array.</span>
-								</li>
-							</ol>
-						</div>
-						<div class="returns">
-							<div class="label">Returns</div>
-							<span>
-								The single element of the array (after applying the given Filter, if applicable), or
-								<code>null</code> if the array has zero elements. An error is thrown if more than one element
-								matches.
-							</span>
-						</div>
-						<script type="application/x.jsapi#tests" jsapi:id="Array.choose">
-							test( module.Array.choose([ 3 ]) == 3 );
-							test( module.Array.choose([]) === null );
-							test( module.Array.choose([ 1, 2, 3 ], function(a) { return a == 3; } ) == 3 );
-						</script>
-					</li>
-				</ul>
-				<!--	TODO	decide whether Array.categorize is experimental	-->
-			</li>
-		</ul>
 	</div>
 </body>
 </html>
diff --git a/js/object/module.fifty.ts b/js/object/module.fifty.ts
index a743d309c..675b4d879 100644
--- a/js/object/module.fifty.ts
+++ b/js/object/module.fifty.ts
@@ -652,7 +652,46 @@ namespace slime.$api.old {
 	)(fifty);
 
 	export interface Exports {
-		Array: any
+		Array: {
+			<T>(ts: Array<T>): Array<T> & { each: any }
+			new <T>(ts: Array<T>): Array<T>
+
+			/**
+			 * Converts an array into a single element. First applies the given Filter, if one is given: the Filter should be a
+			 * filter that only accepts zero or one element of the array.
+
+			 * @param array An array.
+			 * @param filter An optional Filter that is used to preprocess the array.
+			 * @returns The single element of the array (after applying the given Filter, if applicable), or `null` if the array has
+			 * zero elements. An error is thrown if more than one element matches.
+			 */
+			choose: <T>(array: Array<T>, filter?: (t: T) => boolean) => T
+
+			toValue: any
+			categorize: any
+		}
+	}
+
+	(
+		function(
+			fifty: slime.fifty.test.Kit
+		) {
+			const module = old.test.subject;
+
+			const test = function(b) {
+				fifty.verify(b).is(true);
+			};
+
+			fifty.tests.exports.Array = function() {
+				test( module.Array.choose([ 3 ]) == 3 );
+				test( module.Array.choose([]) === null );
+				test( module.Array.choose([ 1, 2, 3 ], function(a) { return a == 3; } ) == 3 );
+			}
+		}
+	//@ts-ignore
+	)(fifty);
+
+	export interface Exports {
 		Error: any
 		Task: any
 
diff --git a/js/object/module.js b/js/object/module.js
index d582a64c3..79e525e71 100644
--- a/js/object/module.js
+++ b/js/object/module.js
@@ -612,19 +612,39 @@
 			};
 		};
 
-		$exports.Array = function(array) {
-			if (this.constructor == arguments.callee.prototype) {
-				//	called with new
-				array = array.slice();
-			}
+		//@ts-ignore Confused because of function called both as constructor and function;
+		$exports.Array = Object.assign(
+			/**
+			 * @param { Array & { one: any, each: any, fold: any, select: any } } array
+			 * @returns { Array & { one: any, each: any, fold: any, select: any } }
+			 */
+			function(array) {
+				if (this.constructor == arguments.callee.prototype) {
+					//	called with new
+					array = Object.assign(
+						array.slice(),
+						{
+							one: void(0),
+							each: void(0),
+							fold: void(0),
+							select: void(0)
+						}
+					);
+				}
 
-			array.one = ArrayMethods.one;
-			array.each = ArrayMethods.each;
-			array.fold = ArrayMethods.fold;
-			array.select = ArrayMethods.select;
+				array.one = ArrayMethods.one;
+				array.each = ArrayMethods.each;
+				array.fold = ArrayMethods.fold;
+				array.select = ArrayMethods.select;
 
-			return array;
-		}
+				return array;
+			},
+			{
+				choose: void(0),
+				toValue: void(0),
+				categorize: void(0)
+			}
+		)
 		for (var x in ArrayMethods) {
 			$exports.Array[x] = (function(underlying) {
 				return function(array) {