Sharkey/packages/backend/src/prelude/maybe.ts
2021-12-09 23:58:30 +09:00

20 lines
307 B
TypeScript

export interface IMaybe<T> {
isJust(): this is IJust<T>;
}
export interface IJust<T> extends IMaybe<T> {
get(): T;
}
export function just<T>(value: T): IJust<T> {
return {
isJust: () => true,
get: () => value,
};
}
export function nothing<T>(): IMaybe<T> {
return {
isJust: () => false,
};
}