@propertyWrapper
struct Memoize<Key: Equatable, Value>: DynamicProperty {
	var wrappedValue: Value {
		fatalError("To use @Memoize, call it as a function, passing the input value(s), and a closure to produce the value")
	}
	
	@State @Boxed private var cache: (key: Key, value: Value)?
	
	init(key keyType: Key.Type = Int.self) {}
	
	private func getMemoized(key: Key, produceValue: () throws -> Value) rethrows -> Value {
		if let cache, cache.key == key {
			return cache.value
		}
		
		let newValue = try produceValue()
		cache = (key: key, value: newValue)
		return newValue
	}
	
	func callAsFunction(_ key: Key, produceValue: () throws -> Value) rethrows -> Value {
		return try getMemoized(key: key, produceValue: produceValue)
	}
	
	func callAsFunction(
		_ key: any Hashable...,
		produceValue: () throws -> Value
	) rethrows -> Value where Key == Int {
		var keyHasher = Hasher()
		
		for keyPart in key {
			keyHasher.combine(keyPart)
		}
		
		return try getMemoized(key: keyHasher.finalize(), produceValue: produceValue)
	}
}

@propertyWrapper
fileprivate class Boxed<Wrapped> {
	var wrappedValue: Wrapped
	
	init(wrappedValue: Wrapped) {
		self.wrappedValue = wrappedValue
	}
}