Type alias RecursivePartial<T>

RecursivePartial<T>: {
    [P in keyof T]?: T[P] extends (infer I)[]
        ? RecursivePartial<I>[]
        : T[P] extends ((...args) => any)
            ? T[P]
            : RecursivePartial<T[P]>
}

Returns a new type with all fields marked optional.

Borrowed from the tsdef module.