Updatestype

{
	/**
	 * Set update (all branches)
	 * - Can set `a` and `a.a1` in `{ a: { a1: 123 } }`
	 * - Sometimes inference gets confused, if that happens use `=` syntax instead.
	 */
	readonly [K in BranchDataPath<T> as `${K}`]?: BranchData<T>[K] | undefined;
} & {
	/**
	 * Set update (leaves only)
	 * - Can set `a.a1` in `{ a: { a1: 123 } }`, but cannot set `a`
	 * - Deeply-nested properties don't always infer when leaves and branches are combined.
	 * - This syntax is more exact and will infer better.
	 */
	readonly [K in LeafDataPath<T> as `=${K}`]?: LeafData<T>[K] | undefined;
} & {
	/**
	 * Sum update.
	 * - Increment/decrement numbers.
	 */
	readonly [K in LeafDataPath<T> as `+=${K}` | `-=${K}`]?: LeafData<T>[K] extends number ? LeafData<T>[K] | undefined : never;
} & {
	/**
	 * With/omit update.
	 * - Add or remove items from arrays.
	 */
	readonly [K in LeafDataPath<T> as `+[]${K}` | `-[]${K}`]?: LeafData<T>[K] extends ImmutableArray<unknown>
		? LeafData<T>[K] | LeafData<T>[K][number] | undefined
		: never;
}