Option - API reference

Optional value container.

Distinguishes absence from values like null or undefined.

Use Option when the value itself can be null or undefined. For APIs where null means "not found", just use T | null directly.

Example

import { isNone, isSome, none, type Option, some } from "@evolu/common";

const cache = new Map<string, Option<unknown>>();

const get = (key: string): Option<unknown> => cache.get(key) ?? none;

cache.set("a", some(null));
cache.set("b", some(undefined));

const a = get("a");
assert(isSome(a));
expect(a.value).toBeNull();
expect(isSome(get("b"))).toBe(true);
expect(isNone(get("c"))).toBe(true);

Utilities

Type Alias	Description
InferOption	Extracts the value type from an Option or Some.

Functions

Function	Description
fromNullable	Converts a nullable value to an Option.
isNone	Type guard for None.
isSome	Type guard for Some.
some	Creates a Some.

Interfaces

Interface	Description
None	Absent value in an Option.
Some	Present value in an Option.

Type Aliases

Type Alias	Description
Option	Optional value.

Variables

Variable	Description
none	Shared None instance.