Option types

modules/option/index.d.ts

@@ -0,0 +1,44 @@
+declare namespace Option {
+	interface Constructor {
+		readonly None: Option<never>;
+
+		Some: <T>(value: NonNullable<T>) => Option<T>;
+		Wrap: <T>(value: T) => Option<T>;
+		Is: (value: unknown) => boolean;
+		Assert: (value: unknown) => void;
+		Deserialize: <T>(data: SerializedOption<T>) => Option<T>;
+	}
+
+	interface SerializedOption<T> {
+		ClassName: "Option";
+		Value?: T;
+	}
+
+	interface Match<T, V> {
+		Some: (value: T) => V;
+		None: () => V;
+	}
+}
+
+interface Option<T> {
+	Serialize(): Option.SerializedOption<T>;
+	Match<V>(match: Option.Match<T, V>): V;
+	IsSome(): boolean;
+	IsNone(): boolean;
+	Expect(msg: string): T;
+	ExpectNone(msg: string): void;
+	Unwrap(): T;
+	UnwrapOr(defaultValue: T): T;
+	UnwrapOrElse(defaultFn: () => T): T;
+	And<O>(optionB: Option<O>): Option<O>;
+	AndThen<V>(andThenFn: (value: T) => V): Option<V>;
+	Or<O>(optionB: Option<O>): Option<T> | Option<O>;
+	OrElse<V>(orElseFn: (value: T) => V): Option<V>;
+	XOr<O>(optionB: Option<O>): Option<T> | Option<O>;
+	Filter(predicate: (value: T) => boolean): Option<T>;
+	Contains(value: T): boolean;
+}
+
+declare const Option: Option.Constructor;
+
+export = Option;