diff --git a/README.md b/README.md
index 080b250..e750ee6 100644
--- a/README.md
+++ b/README.md
@@ -51,22 +51,24 @@ const remainingSubscriptionCount = unsubscribe();
 inViewport.unsubscribeAll(); // Call unsubscribeAll to remove child property/computed subscriptions.
 ```
 
-### Provide a comparator for complex types
+### Provide a hash function for complex types
 
-When storing a type that is not determined to be equal with simple equality (===), provide a
-function to determine in the new provided value should be propagated to dependents.
+When storing a type that is not determined to be equal with simple equality (===), provide a hash
+function to be used for simple comparison to determine if the new provided value should be
+propagated to dependents.
 
 ```js
-function setEquals(a, b) {
-	return (
-		a instanceof Set &&
-		b instanceof Set &&
-		[...a].reduce((acc, d) => acc && b.has(d), true) &&
-		[...b].reduce((acc, d) => acc && a.has(d), true)
-	);
+function hashSet(_a) {
+	if (_a instanceof Set) {
+		return Array.from(_a.keys())
+			.sort()
+			.map(k => `${(typeof k).substr(0, 1)}:${encodeURIComponent(k)}/`)
+			.join('?');
+	}
+	return _a;
 }
 
-const a = prop(new Set([1, 2]), setEquals);
+const a = prop(new Set([1, 2]), hashSet);
 ```
 
 # [computed](./src/computed.js)
@@ -137,28 +139,30 @@ showDialog.detach(); // Call detach to remove this computed from the logic tree.
 showDialog.unsubscribeAll(); // Call unsubscribeAll to remove child property/computed subscriptions.
 ```
 
-### Provide a comparator for complex types
+### Provide a hash function for complex types
 
 When the computed result is a type that is not determined to be equal with simple equality (===),
-provide a function to determine in the new provided value should be propagated to dependents.
+provide a hash function to be used for simple comparison to determine if the new provided value
+should be propagated to dependents.
 
 ```js
-function setEquals(a, b) {
-	return (
-		a instanceof Set &&
-		b instanceof Set &&
-		[...a].reduce((acc, d) => acc && b.has(d), true) &&
-		[...b].reduce((acc, d) => acc && a.has(d), true)
-	);
+function hashSet(_a) {
+	if (_a instanceof Set) {
+		return Array.from(_a.keys())
+			.sort()
+			.map(k => `${(typeof k).substr(0, 1)}:${encodeURIComponent(k)}/`)
+			.join('?');
+	}
+	return _a;
 }
 
 function _intersection(a, b) {
 	return new Set([...a].filter(x => b.has(x)));
 }
 
-const a = prop(new Set([1, 2]), setEquals);
-const b = prop(new Set([2, 3]), setEquals);
-const intersection = computed(_intersection, [a, b], setEquals);
+const a = prop(new Set([1, 2]), hashSet);
+const b = prop(new Set([2, 3]), hashSet);
+const intersection = computed(_intersection, [a, b], hashSet);
 ```
 
 # [bundle](./src/bundle.js)
diff --git a/package.json b/package.json
index 1b9f4de..f71a7ca 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "frptools",
-	"version": "2.0.0",
+	"version": "2.1.0",
 	"description": "Observable Property and Computed data streams",
 	"main": "lib/index.js",
 	"jsnext:main": "src/index.js",
diff --git a/spec/computed.spec.js b/spec/computed.spec.js
index cf6cb50..8b69bde 100644
--- a/spec/computed.spec.js
+++ b/spec/computed.spec.js
@@ -1,4 +1,5 @@
 const { prop, computed } = require('../lib/index.js');
+const { hashSet } = require('../lib/util.js');
 
 describe('computed', () => {
 	const add = (a, b) => a + b;
@@ -157,15 +158,6 @@ describe('computed', () => {
 	});
 
 	it('uses a comparator', () => {
-		function setEquals(a, b) {
-			return (
-				a instanceof Set &&
-				b instanceof Set &&
-				[...a].reduce((acc, d) => acc && b.has(d), true) &&
-				[...b].reduce((acc, d) => acc && a.has(d), true)
-			);
-		}
-
 		let runCount = 0;
 
 		function intersection(a, b) {
@@ -173,9 +165,9 @@ describe('computed', () => {
 			return new Set([...a].filter(x => b.has(x)));
 		}
 
-		const a = prop(new Set([1, 2]), setEquals);
-		const b = prop(new Set([2, 3]), setEquals);
-		const ABintersection = computed(intersection, [a, b], setEquals);
+		const a = prop(new Set([1, 2]), hashSet);
+		const b = prop(new Set([2, 3]), hashSet);
+		const ABintersection = computed(intersection, [a, b], hashSet);
 
 		expect(runCount).toEqual(0);
 		expect([...ABintersection()]).toEqual([2]);
diff --git a/spec/property.spec.js b/spec/property.spec.js
index 05a49e0..f42d60d 100644
--- a/spec/property.spec.js
+++ b/spec/property.spec.js
@@ -1,4 +1,5 @@
 const { prop } = require('../lib/index.js');
+const { hashSet } = require('../lib/util.js');
 
 describe('A property', () => {
 	it('returns its initialized value', () => {
@@ -62,19 +63,10 @@ describe('A property', () => {
 		expect(runCount).toEqual(3);
 	});
 
-	it('uses a comparator', () => {
-		function setEquals(a, b) {
-			return (
-				a instanceof Set &&
-				b instanceof Set &&
-				[...a].reduce((acc, d) => acc && b.has(d), true) &&
-				[...b].reduce((acc, d) => acc && a.has(d), true)
-			);
-		}
-
+	it('uses a hash function', () => {
 		let runCount = 0;
 
-		const a = prop(new Set([1, 2]), setEquals);
+		const a = prop(new Set([1, 2]), hashSet);
 		a.subscribe(() => (runCount += 1));
 		expect([...a()]).toEqual([1, 2]);
 		expect(runCount).toEqual(0);
diff --git a/src/computed.js b/src/computed.js
index b622652..40e25a9 100644
--- a/src/computed.js
+++ b/src/computed.js
@@ -1,10 +1,11 @@
-import { eq } from './util.js';
+import { id } from './util.js';
 
-export function computed(fn, dependencies = [], comparator = eq) {
+export function computed(fn, dependencies = [], hash = id) {
 	const subscribers = new Set();
 	const dependents = new Set();
 	let isDirty = true;
 	let val;
+	let id;
 
 	// Receive dirty flag from parent logic node (dependency).  Pass it down.
 	function _computedDirtyReporter(_, skipPropagation) {
@@ -25,7 +26,9 @@ export function computed(fn, dependencies = [], comparator = eq) {
 		if (isDirty) {
 			const newVal = fn.apply(null, dependencies.map(runParam));
 			isDirty = false;
-			if (!comparator(val, newVal)) {
+			const newId = hash(newVal);
+			if (id !== newId) {
+				id = newId;
 				val = newVal;
 				subscribers.forEach(s => s(val));
 			}
diff --git a/src/property.js b/src/property.js
index c3719c3..3f431c1 100644
--- a/src/property.js
+++ b/src/property.js
@@ -1,10 +1,13 @@
-import { eq } from './util.js';
+import { id } from './util.js';
 
-export function prop(store, comparator = eq) {
+export function prop(store, hash = id) {
 	const subscribers = new Set();
+	let id = hash(store);
 
 	const accessor = function _prop(newVal) {
-		if (newVal !== undefined && !comparator(store, newVal)) {
+		const newId = hash(newVal);
+		if (newVal !== undefined && id !== newId) {
+			id = newId;
 			store = newVal;
 			subscribers.forEach(s => s(store));
 		}
diff --git a/src/util.js b/src/util.js
index 4ce0d59..251a894 100644
--- a/src/util.js
+++ b/src/util.js
@@ -1 +1,11 @@
-export const eq = (a, b) => a === b;
+export const id = a => a;
+
+export function hashSet(_a) {
+	if (_a instanceof Set) {
+		return Array.from(_a.keys())
+			.sort()
+			.map(k => `${(typeof k).substr(0, 1)}:${encodeURIComponent(k)}/`)
+			.join('?');
+	}
+	return _a;
+}