Type helpers

types.ts

export type MakeOptional<Type, Key extends keyof Type> = Omit<Type, Key> &
  Partial<Pick<Type, Key>>;

export type PickNullable<T> = {
  [P in keyof T as null extends T[P] ? P : never]: T[P];
};

export type PickNotNullable<T> = {
  [P in keyof T as null extends T[P] ? never : P]: T[P];
};

export type OptionalNullable<T> = T extends object
  ? {
      [K in keyof PickNullable<T>]?: OptionalNullable<Exclude<T[K], null>>;
    } & {
      [K in keyof PickNotNullable<T>]: OptionalNullable<T[K]>;
    }
  : T;

// expands object types one level deep
export type Expand<T> = T extends infer O ? { [K in keyof O]: O[K] } : never;

// expands object types recursively
// prettier-ignore
export type ExpandRecursively<T> =
  T extends Date ? T  // don't expand dates
  : T extends object ?
      T extends infer O ? { [K in keyof O]: ExpandRecursively<O[K]> }
      : never
    : T;