diff --git a/readme.md b/readme.md
index 9d0d687..1da8fea 100644
--- a/readme.md
+++ b/readme.md
@@ -94,6 +94,16 @@ Returns a predicate that verifies if the value matches at least one of the given
 ow('foo', ow.any(ow.string.maxLength(3), ow.number));
 ```
 
+### ow.optional.{type}
+
+Makes the predicate optional. An optional predicate means that it doesn't fail if the value is `undefined`.
+
+```ts
+ow(1, ow.optional.number);
+
+ow(undefined, ow.optional.number);
+```
+
 ### ow.{type}
 
 All the below types return a predicate. Every predicate has some extra operators that you can use to test the value even more fine-grained.
diff --git a/source/index.ts b/source/index.ts
index 0d86e1f..bc641bb 100644
--- a/source/index.ts
+++ b/source/index.ts
@@ -1,28 +1,17 @@
 import callsites from 'callsites';
 import {inferLabel} from './lib/utils/infer-label';
 import {Predicate} from './lib/predicates/predicate';
-import {AnyPredicate} from './lib/predicates/any';
 import {testSymbol, BasePredicate, isPredicate} from './lib/predicates/base-predicate';
-import {StringPredicate} from './lib/predicates/string';
-import {NumberPredicate} from './lib/predicates/number';
-import {BooleanPredicate} from './lib/predicates/boolean';
-import {ArrayPredicate} from './lib/predicates/array';
-import {ObjectPredicate} from './lib/predicates/object';
-import {DatePredicate} from './lib/predicates/date';
-import {ErrorPredicate} from './lib/predicates/error';
-import {MapPredicate} from './lib/predicates/map';
-import {WeakMapPredicate} from './lib/predicates/weak-map';
-import {SetPredicate} from './lib/predicates/set';
-import {WeakSetPredicate} from './lib/predicates/weak-set';
-
-type TypedArray = Int8Array | Uint8Array | Uint8ClampedArray | Int16Array | Uint16Array | Int32Array | Uint32Array | Float32Array | Float64Array;
+import modifiers, {Modifiers} from './modifiers';
+import predicates, {Predicates} from './predicates';
 
 /**
  * @hidden
  */
 export type Main = <T>(value: T, label: string | Function, predicate: BasePredicate<T>) => void;
 
-export interface Ow {
+// Extends is only necessary for the generated documentation to be cleaner. The loaders below infer the correct type.
+export interface Ow extends Modifiers, Predicates {
 	/**
 	 * Test if the value matches the predicate. Throws an `ArgumentError` if the test fails.
 	 *
@@ -38,138 +27,6 @@ export interface Ow {
 	 * @param predicate Predicate to test against.
 	 */
 	<T>(value: T, label: string, predicate: BasePredicate<T>): void;
-	/**
-	 * Test the value to be a string.
-	 */
-	readonly string: StringPredicate;
-	/**
-	 * Test the value to be a number.
-	 */
-	readonly number: NumberPredicate;
-	/**
-	 * Test the value to be a boolean.
-	 */
-	readonly boolean: BooleanPredicate;
-	/**
-	 * Test the value to be undefined.
-	 */
-	readonly undefined: Predicate<undefined>;
-	/**
-	 * Test the value to be null.
-	 */
-	readonly null: Predicate<null>;
-	/**
-	 * Test the value to be null or undefined.
-	 */
-	readonly nullOrUndefined: Predicate<null | undefined>;
-	/**
-	 * Test the value to be not a number.
-	 */
-	readonly nan: Predicate<number>;
-	/**
-	 * Test the value to be a Symbol.
-	 */
-	readonly symbol: Predicate<Symbol>;
-	/**
-	 * Test the value to be an array.
-	 */
-	readonly array: ArrayPredicate;
-	/**
-	 * Test the value to be an object.
-	 */
-	readonly object: ObjectPredicate;
-	/**
-	 * Test the value to be a Date.
-	 */
-	readonly date: DatePredicate;
-	/**
-	 * Test the value to be an Error.
-	 */
-	readonly error: ErrorPredicate;
-	/**
-	 * Test the value to be a Map.
-	 */
-	readonly map: MapPredicate;
-	/**
-	 * Test the value to be a WeakMap.
-	 */
-	readonly weakMap: WeakMapPredicate;
-	/**
-	 * Test the value to be a Set.
-	 */
-	readonly set: SetPredicate;
-	/**
-	 * Test the value to be a WeakSet.
-	 */
-	readonly weakSet: WeakSetPredicate;
-	/**
-	 * Test the value to be a Function.
-	 */
-	readonly function: Predicate<Function>;
-	/**
-	 * Test the value to be a Buffer.
-	 */
-	readonly buffer: Predicate<Buffer>;
-	/**
-	 * Test the value to be a RegExp.
-	 */
-	readonly regExp: Predicate<RegExp>;
-	/**
-	 * Test the value to be a Promise.
-	 */
-	readonly promise: Predicate<Promise<any>>;
-	/**
-	 * Test the value to be a typed array.
-	 */
-	readonly typedArray: Predicate<TypedArray>;
-	/**
-	 * Test the value to be a Int8Array.
-	 */
-	readonly int8Array: Predicate<Int8Array>;
-	/**
-	 * Test the value to be a Uint8Array.
-	 */
-	readonly uint8Array: Predicate<Uint8Array>;
-	/**
-	 * Test the value to be a Uint8ClampedArray.
-	 */
-	readonly uint8ClampedArray: Predicate<Uint8ClampedArray>;
-	/**
-	 * Test the value to be a Int16Array.
-	 */
-	readonly int16Array: Predicate<Int16Array>;
-	/**
-	 * Test the value to be a Uint16Array.
-	 */
-	readonly uint16Array: Predicate<Uint16Array>;
-	/**
-	 * Test the value to be a Int32Array.
-	 */
-	readonly int32Array: Predicate<Int32Array>;
-	/**
-	 * Test the value to be a Uint32Array.
-	 */
-	readonly uint32Array: Predicate<Uint32Array>;
-	/**
-	 * Test the value to be a Float32Array.
-	 */
-	readonly float32Array: Predicate<Float32Array>;
-	/**
-	 * Test the value to be a Float64Array.
-	 */
-	readonly float64Array: Predicate<Float64Array>;
-	/**
-	 * Test the value to be a ArrayBuffer.
-	 */
-	readonly arrayBuffer: Predicate<ArrayBuffer>;
-	/**
-	 * Test the value to be a DataView.
-	 */
-	readonly dataView: Predicate<DataView>;
-	/**
-	 * Test the value to be Iterable.
-	 */
-	readonly iterable: Predicate<Iterable<any>>;
 	/**
 	 * Returns `true` if the value matches the predicate, otherwise returns `false`.
 	 *
@@ -190,20 +47,6 @@ export interface Ow {
 	 * @param predicate Predicate used in the validator function.
 	 */
 	create<T>(label: string, predicate: BasePredicate<T>): (value: T) => void;
-	/**
-	 * Test that the value matches at least one of the given predicates.
-	 */
-	any<T1>(p1: BasePredicate<T1>): AnyPredicate<T1>;
-	any<T1, T2>(p1: BasePredicate<T1>, p2: BasePredicate<T2>): AnyPredicate<T1 | T2>;
-	any<T1, T2, T3>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>): AnyPredicate<T1 | T2 | T3>;
-	any<T1, T2, T3, T4>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>): AnyPredicate<T1 | T2 | T3 | T4>;
-	any<T1, T2, T3, T4, T5>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>): AnyPredicate<T1 | T2 | T3 | T4 | T5>;
-	any<T1, T2, T3, T4, T5, T6>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6>;
-	any<T1, T2, T3, T4, T5, T6, T7>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7>;
-	any<T1, T2, T3, T4, T5, T6, T7, T8>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>, p8: BasePredicate<T8>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8>;
-	any<T1, T2, T3, T4, T5, T6, T7, T8, T9>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>, p8: BasePredicate<T8>, p9: BasePredicate<T9>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9>;
-	any<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>, p8: BasePredicate<T8>, p9: BasePredicate<T9>, p10: BasePredicate<T10>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10>;
-	any(...predicate: BasePredicate[]): AnyPredicate;
 }
 
 const test = <T>(value: T, label: string | Function, predicate: BasePredicate<T>) => {
@@ -250,116 +93,12 @@ Object.defineProperties(ow, {
 
 			test(value, labelOrPredicate as string, predicate as BasePredicate<T>);
 		}
-	},
-	any: {
-		value: (...predicates: BasePredicate[]) => new AnyPredicate(predicates)
-	},
-	string: {
-		get: () => new StringPredicate()
-	},
-	number: {
-		get: () => new NumberPredicate()
-	},
-	boolean: {
-		get: () => new BooleanPredicate()
-	},
-	undefined: {
-		get: () => new Predicate('undefined')
-	},
-	null: {
-		get: () => new Predicate('null')
-	},
-	nullOrUndefined: {
-		get: () => new Predicate('nullOrUndefined')
-	},
-	nan: {
-		get: () => new Predicate('nan')
-	},
-	symbol: {
-		get: () => new Predicate('symbol')
-	},
-	array: {
-		get: () => new ArrayPredicate()
-	},
-	object: {
-		get: () => new ObjectPredicate()
-	},
-	date: {
-		get: () => new DatePredicate()
-	},
-	error: {
-		get: () => new ErrorPredicate()
-	},
-	map: {
-		get: () => new MapPredicate()
-	},
-	weakMap: {
-		get: () => new WeakMapPredicate()
-	},
-	set: {
-		get: () => new SetPredicate()
-	},
-	weakSet: {
-		get: () => new WeakSetPredicate()
-	},
-	function: {
-		get: () => new Predicate('Function')
-	},
-	buffer: {
-		get: () => new Predicate('Buffer')
-	},
-	regExp: {
-		get: () => new Predicate('RegExp')
-	},
-	promise: {
-		get: () => new Predicate('Promise')
-	},
-	typedArray: {
-		get: () => new Predicate('TypedArray')
-	},
-	int8Array: {
-		get: () => new Predicate('Int8Array')
-	},
-	uint8Array: {
-		get: () => new Predicate('Uint8Array')
-	},
-	uint8ClampedArray: {
-		get: () => new Predicate('Uint8ClampedArray')
-	},
-	int16Array: {
-		get: () => new Predicate('Int16Array')
-	},
-	uint16Array: {
-		get: () => new Predicate('Uint16Array')
-	},
-	int32Array: {
-		get: () => new Predicate('Int32Array')
-	},
-	uint32Array: {
-		get: () => new Predicate('Uint32Array')
-	},
-	float32Array: {
-		get: () => new Predicate('Float32Array')
-	},
-	float64Array: {
-		get: () => new Predicate('Float64Array')
-	},
-	arrayBuffer: {
-		get: () => new Predicate('ArrayBuffer')
-	},
-	dataView: {
-		get: () => new Predicate('DataView')
-	},
-	iterable: {
-		get: () => new Predicate('Iterable')
 	}
 });
 
-export default ow as Ow;
+export default predicates(modifiers(ow)) as Ow;
+export {BasePredicate, Predicate};
 export {
-	BasePredicate,
-	Predicate,
-	AnyPredicate,
 	StringPredicate,
 	NumberPredicate,
 	BooleanPredicate,
@@ -370,5 +109,6 @@ export {
 	MapPredicate,
 	WeakMapPredicate,
 	SetPredicate,
-	WeakSetPredicate
-};
+	WeakSetPredicate,
+	AnyPredicate
+} from './predicates';
diff --git a/source/lib/predicates/any.ts b/source/lib/predicates/any.ts
index 7aabc1c..73e93c8 100644
--- a/source/lib/predicates/any.ts
+++ b/source/lib/predicates/any.ts
@@ -1,13 +1,15 @@
 import {ArgumentError} from '../argument-error';
 import {BasePredicate, testSymbol} from './base-predicate';
 import {Main} from '../..';
+import {PredicateOptions} from './predicate';
 
 /**
  * @hidden
  */
 export class AnyPredicate<T = any> implements BasePredicate<T> {
 	constructor(
-		private readonly predicates: BasePredicate[]
+		private readonly predicates: BasePredicate[],
+		private readonly options: PredicateOptions = {}
 	) {}
 
 	// tslint:disable completed-docs
@@ -22,6 +24,10 @@ export class AnyPredicate<T = any> implements BasePredicate<T> {
 
 				return;
 			} catch (err) {
+				if (value === undefined && this.options.optional === true) {
+					return;
+				}
+
 				errors.push(`- ${err.message}`);
 			}
 		}
diff --git a/source/lib/predicates/array.ts b/source/lib/predicates/array.ts
index e02a8d2..5ef610c 100644
--- a/source/lib/predicates/array.ts
+++ b/source/lib/predicates/array.ts
@@ -1,13 +1,13 @@
 import isEqual from 'lodash.isequal';
 import ow from '../..';
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 
 export class ArrayPredicate<T = any> extends Predicate<T[]> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<T[]>) {
-		super('array', context);
+	constructor(options?: PredicateOptions) {
+		super('array', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/boolean.ts b/source/lib/predicates/boolean.ts
index 0187c88..544c4c4 100644
--- a/source/lib/predicates/boolean.ts
+++ b/source/lib/predicates/boolean.ts
@@ -1,11 +1,11 @@
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 
 export class BooleanPredicate extends Predicate<boolean> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<boolean>) {
-		super('boolean', context);
+	constructor(options?: PredicateOptions) {
+		super('boolean', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/date.ts b/source/lib/predicates/date.ts
index 76190ef..c89afeb 100644
--- a/source/lib/predicates/date.ts
+++ b/source/lib/predicates/date.ts
@@ -1,11 +1,11 @@
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 
 export class DatePredicate extends Predicate<Date> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<Date>) {
-		super('date', context);
+	constructor(options?: PredicateOptions) {
+		super('date', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/error.ts b/source/lib/predicates/error.ts
index 30f1d37..1e57988 100644
--- a/source/lib/predicates/error.ts
+++ b/source/lib/predicates/error.ts
@@ -1,11 +1,11 @@
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 
 export class ErrorPredicate extends Predicate<Error> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<Error>) {
-		super('error', context);
+	constructor(options?: PredicateOptions) {
+		super('error', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/map.ts b/source/lib/predicates/map.ts
index fdfeffe..c110ea6 100644
--- a/source/lib/predicates/map.ts
+++ b/source/lib/predicates/map.ts
@@ -1,5 +1,5 @@
 import isEqual from 'lodash.isequal';
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 import hasItems from '../utils/has-items';
 import ofType from '../utils/of-type';
 
@@ -7,8 +7,8 @@ export class MapPredicate<T1 = any, T2 = any> extends Predicate<Map<T1, T2>> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<Map<T1, T2>>) {
-		super('Map', context);
+	constructor(options?: PredicateOptions) {
+		super('Map', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/number.ts b/source/lib/predicates/number.ts
index c6d2664..568ebfa 100644
--- a/source/lib/predicates/number.ts
+++ b/source/lib/predicates/number.ts
@@ -1,12 +1,12 @@
 import is from '@sindresorhus/is';
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 
 export class NumberPredicate extends Predicate<number> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<number>) {
-		super('number', context);
+	constructor(options?: PredicateOptions) {
+		super('number', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/object.ts b/source/lib/predicates/object.ts
index bf8a590..214d90e 100644
--- a/source/lib/predicates/object.ts
+++ b/source/lib/predicates/object.ts
@@ -1,7 +1,7 @@
 import is from '@sindresorhus/is';
 import dotProp from 'dot-prop';
 import isEqual from 'lodash.isequal';
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 import hasItems from '../utils/has-items';
 import ofType from '../utils/of-type';
 import ofTypeDeep from '../utils/of-type-deep';
@@ -10,8 +10,8 @@ export class ObjectPredicate extends Predicate<object> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<object>) {
-		super('object', context);
+	constructor(options?: PredicateOptions) {
+		super('object', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/predicate.ts b/source/lib/predicates/predicate.ts
index 38adb2e..e75713c 100644
--- a/source/lib/predicates/predicate.ts
+++ b/source/lib/predicates/predicate.ts
@@ -18,9 +18,15 @@ export interface Validator<T> {
 /**
  * @hidden
  */
-export interface Context<T> {
+export interface PredicateOptions {
+	optional?: boolean;
+}
+
+/**
+ * @hidden
+ */
+export interface Context<T = unknown> extends PredicateOptions {
 	validators: Validator<T>[];
-	label?: string;
 }
 
 /**
@@ -32,12 +38,19 @@ export const validatorSymbol = Symbol('validators');
  * @hidden
  */
 export class Predicate<T = any> implements BasePredicate<T> {
+	private readonly context: Context<T> = {
+		validators: []
+	};
+
 	constructor(
 		private readonly type: string,
-		private readonly context: Context<T> = {
-			validators: []
-		}
+		private readonly options: PredicateOptions = {}
 	) {
+		this.context = {
+			...this.context,
+			...this.options
+		};
+
 		const x = this.type[0].toLowerCase() + this.type.slice(1);
 
 		this.addValidator({
@@ -59,7 +72,7 @@ export class Predicate<T = any> implements BasePredicate<T> {
 		for (const {validator, message} of this.context.validators) {
 			const result = validator(value);
 
-			if (result === true) {
+			if (result === true || (this.options.optional === true && value === undefined)) {
 				continue;
 			}
 
diff --git a/source/lib/predicates/set.ts b/source/lib/predicates/set.ts
index 88bd4a9..053fe5d 100644
--- a/source/lib/predicates/set.ts
+++ b/source/lib/predicates/set.ts
@@ -1,5 +1,5 @@
 import isEqual from 'lodash.isequal';
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 import hasItems from '../utils/has-items';
 import ofType from '../utils/of-type';
 
@@ -7,8 +7,8 @@ export class SetPredicate<T = any> extends Predicate<Set<T>> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<Set<T>>) {
-		super('Set', context);
+	constructor(options?: PredicateOptions) {
+		super('Set', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/string.ts b/source/lib/predicates/string.ts
index a49f8ff..4aff42f 100644
--- a/source/lib/predicates/string.ts
+++ b/source/lib/predicates/string.ts
@@ -1,12 +1,12 @@
 import valiDate from 'vali-date';
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 
 export class StringPredicate extends Predicate<string> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<string>) {
-		super('string', context);
+	constructor(options?: PredicateOptions) {
+		super('string', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/weak-map.ts b/source/lib/predicates/weak-map.ts
index fcf40a5..0bdfe84 100644
--- a/source/lib/predicates/weak-map.ts
+++ b/source/lib/predicates/weak-map.ts
@@ -1,12 +1,12 @@
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 import hasItems from '../utils/has-items';
 
 export class WeakMapPredicate<T1 extends object = any, T2 = any> extends Predicate<WeakMap<T1, T2>> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<WeakMap<T1, T2>>) {
-		super('WeakMap', context);
+	constructor(options?: PredicateOptions) {
+		super('WeakMap', options);
 	}
 
 	/**
diff --git a/source/lib/predicates/weak-set.ts b/source/lib/predicates/weak-set.ts
index 9b08064..9d854f7 100644
--- a/source/lib/predicates/weak-set.ts
+++ b/source/lib/predicates/weak-set.ts
@@ -1,12 +1,12 @@
-import {Predicate, Context} from './predicate';
+import {Predicate, PredicateOptions} from './predicate';
 import hasItems from '../utils/has-items';
 
 export class WeakSetPredicate<T extends object = any> extends Predicate<WeakSet<T>> {
 	/**
 	 * @hidden
 	 */
-	constructor(context?: Context<WeakSet<T>>) {
-		super('WeakSet', context);
+	constructor(options?: PredicateOptions) {
+		super('WeakSet', options);
 	}
 
 	/**
diff --git a/source/modifiers.ts b/source/modifiers.ts
new file mode 100644
index 0000000..4738838
--- /dev/null
+++ b/source/modifiers.ts
@@ -0,0 +1,18 @@
+import predicates, {Predicates} from './predicates';
+
+export interface Modifiers {
+	/**
+	 * Make the following predicate optional so it doesn't fail when the value is `undefined`.
+	 */
+	readonly optional: Predicates;
+}
+
+export default <T>(object: T): T & Modifiers => {
+	Object.defineProperties(object, {
+		optional: {
+			get: () => predicates({}, {optional: true})
+		}
+	});
+
+	return object as T & Modifiers;
+};
diff --git a/source/predicates.ts b/source/predicates.ts
new file mode 100644
index 0000000..9eea045
--- /dev/null
+++ b/source/predicates.ts
@@ -0,0 +1,289 @@
+import {StringPredicate} from './lib/predicates/string';
+import {NumberPredicate} from './lib/predicates/number';
+import {BooleanPredicate} from './lib/predicates/boolean';
+import {Predicate, PredicateOptions} from './lib/predicates/predicate';
+import {ArrayPredicate} from './lib/predicates/array';
+import {ObjectPredicate} from './lib/predicates/object';
+import {DatePredicate} from './lib/predicates/date';
+import {ErrorPredicate} from './lib/predicates/error';
+import {MapPredicate} from './lib/predicates/map';
+import {WeakMapPredicate} from './lib/predicates/weak-map';
+import {SetPredicate} from './lib/predicates/set';
+import {WeakSetPredicate} from './lib/predicates/weak-set';
+import {BasePredicate} from './lib/predicates/base-predicate';
+import {AnyPredicate} from './lib/predicates/any';
+
+type TypedArray = Int8Array | Uint8Array | Uint8ClampedArray | Int16Array | Uint16Array | Int32Array | Uint32Array | Float32Array | Float64Array;
+
+export interface Predicates {
+	/**
+	 * Test the value to be a string.
+	 */
+	readonly string: StringPredicate;
+	/**
+	 * Test the value to be a number.
+	 */
+	readonly number: NumberPredicate;
+	/**
+	 * Test the value to be a boolean.
+	 */
+	readonly boolean: BooleanPredicate;
+	/**
+	 * Test the value to be undefined.
+	 */
+	readonly undefined: Predicate<undefined>;
+	/**
+	 * Test the value to be null.
+	 */
+	readonly null: Predicate<null>;
+	/**
+	 * Test the value to be null or undefined.
+	 */
+	readonly nullOrUndefined: Predicate<null | undefined>;
+	/**
+	 * Test the value to be not a number.
+	 */
+	readonly nan: Predicate<number>;
+	/**
+	 * Test the value to be a Symbol.
+	 */
+	readonly symbol: Predicate<Symbol>;
+	/**
+	 * Test the value to be an array.
+	 */
+	readonly array: ArrayPredicate;
+	/**
+	 * Test the value to be an object.
+	 */
+	readonly object: ObjectPredicate;
+	/**
+	 * Test the value to be a Date.
+	 */
+	readonly date: DatePredicate;
+	/**
+	 * Test the value to be an Error.
+	 */
+	readonly error: ErrorPredicate;
+	/**
+	 * Test the value to be a Map.
+	 */
+	readonly map: MapPredicate;
+	/**
+	 * Test the value to be a WeakMap.
+	 */
+	readonly weakMap: WeakMapPredicate;
+	/**
+	 * Test the value to be a Set.
+	 */
+	readonly set: SetPredicate;
+	/**
+	 * Test the value to be a WeakSet.
+	 */
+	readonly weakSet: WeakSetPredicate;
+	/**
+	 * Test the value to be a Function.
+	 */
+	readonly function: Predicate<Function>;
+	/**
+	 * Test the value to be a Buffer.
+	 */
+	readonly buffer: Predicate<Buffer>;
+	/**
+	 * Test the value to be a RegExp.
+	 */
+	readonly regExp: Predicate<RegExp>;
+	/**
+	 * Test the value to be a Promise.
+	 */
+	readonly promise: Predicate<Promise<any>>;
+	/**
+	 * Test the value to be a typed array.
+	 */
+	readonly typedArray: Predicate<TypedArray>;
+	/**
+	 * Test the value to be a Int8Array.
+	 */
+	readonly int8Array: Predicate<Int8Array>;
+	/**
+	 * Test the value to be a Uint8Array.
+	 */
+	readonly uint8Array: Predicate<Uint8Array>;
+	/**
+	 * Test the value to be a Uint8ClampedArray.
+	 */
+	readonly uint8ClampedArray: Predicate<Uint8ClampedArray>;
+	/**
+	 * Test the value to be a Int16Array.
+	 */
+	readonly int16Array: Predicate<Int16Array>;
+	/**
+	 * Test the value to be a Uint16Array.
+	 */
+	readonly uint16Array: Predicate<Uint16Array>;
+	/**
+	 * Test the value to be a Int32Array.
+	 */
+	readonly int32Array: Predicate<Int32Array>;
+	/**
+	 * Test the value to be a Uint32Array.
+	 */
+	readonly uint32Array: Predicate<Uint32Array>;
+	/**
+	 * Test the value to be a Float32Array.
+	 */
+	readonly float32Array: Predicate<Float32Array>;
+	/**
+	 * Test the value to be a Float64Array.
+	 */
+	readonly float64Array: Predicate<Float64Array>;
+	/**
+	 * Test the value to be a ArrayBuffer.
+	 */
+	readonly arrayBuffer: Predicate<ArrayBuffer>;
+	/**
+	 * Test the value to be a DataView.
+	 */
+	readonly dataView: Predicate<DataView>;
+	/**
+	 * Test the value to be Iterable.
+	 */
+	readonly iterable: Predicate<Iterable<any>>;
+	/**
+	 * Test that the value matches at least one of the given predicates.
+	 */
+	any<T1>(p1: BasePredicate<T1>): AnyPredicate<T1>;
+	any<T1, T2>(p1: BasePredicate<T1>, p2: BasePredicate<T2>): AnyPredicate<T1 | T2>;
+	any<T1, T2, T3>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>): AnyPredicate<T1 | T2 | T3>;
+	any<T1, T2, T3, T4>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>): AnyPredicate<T1 | T2 | T3 | T4>;
+	any<T1, T2, T3, T4, T5>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>): AnyPredicate<T1 | T2 | T3 | T4 | T5>;
+	any<T1, T2, T3, T4, T5, T6>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6>;
+	any<T1, T2, T3, T4, T5, T6, T7>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7>;
+	any<T1, T2, T3, T4, T5, T6, T7, T8>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>, p8: BasePredicate<T8>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8>;
+	any<T1, T2, T3, T4, T5, T6, T7, T8, T9>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>, p8: BasePredicate<T8>, p9: BasePredicate<T9>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9>;
+	any<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(p1: BasePredicate<T1>, p2: BasePredicate<T2>, p3: BasePredicate<T3>, p4: BasePredicate<T4>, p5: BasePredicate<T5>, p6: BasePredicate<T6>, p7: BasePredicate<T7>, p8: BasePredicate<T8>, p9: BasePredicate<T9>, p10: BasePredicate<T10>): AnyPredicate<T1 | T2 | T3 | T4 | T5 | T6 | T7 | T8 | T9 | T10>;
+	any(...predicate: BasePredicate[]): AnyPredicate;
+}
+
+export default <T>(object: T, options?: PredicateOptions): T & Predicates => {
+	Object.defineProperties(object, {
+		string: {
+			get: () => new StringPredicate(options)
+		},
+		number: {
+			get: () => new NumberPredicate(options)
+		},
+		boolean: {
+			get: () => new BooleanPredicate(options)
+		},
+		undefined: {
+			get: () => new Predicate('undefined', options)
+		},
+		null: {
+			get: () => new Predicate('null', options)
+		},
+		nullOrUndefined: {
+			get: () => new Predicate('nullOrUndefined', options)
+		},
+		nan: {
+			get: () => new Predicate('nan', options)
+		},
+		symbol: {
+			get: () => new Predicate('symbol', options)
+		},
+		array: {
+			get: () => new ArrayPredicate(options)
+		},
+		object: {
+			get: () => new ObjectPredicate(options)
+		},
+		date: {
+			get: () => new DatePredicate(options)
+		},
+		error: {
+			get: () => new ErrorPredicate(options)
+		},
+		map: {
+			get: () => new MapPredicate(options)
+		},
+		weakMap: {
+			get: () => new WeakMapPredicate(options)
+		},
+		set: {
+			get: () => new SetPredicate(options)
+		},
+		weakSet: {
+			get: () => new WeakSetPredicate(options)
+		},
+		function: {
+			get: () => new Predicate('Function', options)
+		},
+		buffer: {
+			get: () => new Predicate('Buffer', options)
+		},
+		regExp: {
+			get: () => new Predicate('RegExp', options)
+		},
+		promise: {
+			get: () => new Predicate('Promise', options)
+		},
+		typedArray: {
+			get: () => new Predicate('TypedArray', options)
+		},
+		int8Array: {
+			get: () => new Predicate('Int8Array', options)
+		},
+		uint8Array: {
+			get: () => new Predicate('Uint8Array', options)
+		},
+		uint8ClampedArray: {
+			get: () => new Predicate('Uint8ClampedArray', options)
+		},
+		int16Array: {
+			get: () => new Predicate('Int16Array', options)
+		},
+		uint16Array: {
+			get: () => new Predicate('Uint16Array', options)
+		},
+		int32Array: {
+			get: () => new Predicate('Int32Array', options)
+		},
+		uint32Array: {
+			get: () => new Predicate('Uint32Array', options)
+		},
+		float32Array: {
+			get: () => new Predicate('Float32Array', options)
+		},
+		float64Array: {
+			get: () => new Predicate('Float64Array', options)
+		},
+		arrayBuffer: {
+			get: () => new Predicate('ArrayBuffer', options)
+		},
+		dataView: {
+			get: () => new Predicate('DataView', options)
+		},
+		iterable: {
+			get: () => new Predicate('Iterable', options)
+		},
+		any: {
+			value: (...predicates: BasePredicate[]) => new AnyPredicate(predicates, options)
+		}
+	});
+
+	return object as T & Predicates;
+};
+
+export {
+	StringPredicate,
+	NumberPredicate,
+	BooleanPredicate,
+	ArrayPredicate,
+	ObjectPredicate,
+	DatePredicate,
+	ErrorPredicate,
+	MapPredicate,
+	WeakMapPredicate,
+	SetPredicate,
+	WeakSetPredicate,
+	AnyPredicate
+};
diff --git a/source/test/optional.ts b/source/test/optional.ts
new file mode 100644
index 0000000..17938b2
--- /dev/null
+++ b/source/test/optional.ts
@@ -0,0 +1,10 @@
+import test from 'ava';
+import m from '..';
+
+test('optional', t => {
+	t.notThrows(() => m(1, m.optional.number));
+	t.notThrows(() => m(undefined, m.optional.number));
+	t.notThrows(() => m(undefined, m.optional.any(m.string, m.number)));
+	t.throws(() => m(null, m.optional.number), 'Expected argument to be of type `number` but received type `null`');
+	t.throws(() => m('1' as any, m.optional.number), 'Expected argument to be of type `number` but received type `string`');
+});