Fully unwraps nested Optionals hidden behind "Any"

FlatOptional.swift

protocol _TypeerasedOptional {

	var typeerasedSelf: Any? { get }
}


extension Optional: _TypeerasedOptional {

	var typeerasedSelf: Any? {
		guard let value = self else {
			return nil
		}

		return value
	}
}


func flatOptional(_ value: Any) -> Any? {
	guard let optional = value as? _TypeerasedOptional else {
		return value
	}

	return optional.typeerasedSelf.map(flatOptional)
}


func flatOptional(_ value: Any?) -> Any? {
	return value.flatMap(flatOptional)
}


func flatOptional<Value>(_ value: Any) -> Value? {
	guard let optional = value as? _TypeerasedOptional else {
		return value as? Value
	}

	return optional.typeerasedSelf.flatMap(flatOptional)
}


func flatOptional<Value>(_ value: Any?) -> Value? {
	return value.flatMap(flatOptional)
}



let wrapped = Optional(Optional(Optional(Optional(Optional(Optional(2)))))) as Any
// 'wrapped' is of type 'Any' holding an 'Optional<Optional<Optional<Optional<Optional<Optional<Int>>>>>>' of value '2'
print(wrapped) // prints 'Optional(Optional(Optional(Optional(Optional(Optional(2))))))'

if let unwrapped = flatOptional(wrapped) {
	// 'unwrapped' is of type 'Any' holding an 'Int' of value '2'
	print(unwrapped) // prints '2'
}

if let unwrapped: Int = flatOptional(wrapped) {
	// 'unwrapped' is of type 'Int'
	print(unwrapped) // prints '2'
}