 	}
 }
 
-private class Suspend<T> : Free<T> {
+private class Suspend<T> : FreeId<T> {
 	let suspension : Box<() -> Trampoline<T>>
 	
 	init(s : Box<() -> Trampoline<T>>) {
 		self.suspension = s
 	}
 	
-	private override func fold<R>(norm : Free<T> -> R, codense : Codensity<T> -> R) -> R {
+	private override func fold<R>(norm : FreeId<T> -> R, codense : Codensity<T> -> R) -> R {
 		return norm(self)
 	}
 	

		return undefined()
	}
	
	func flatMap<B>(f : T -> Free<B>) -> Free<B> {
		return liftCodense(self, f)
	}
}

private class Pure<T> : Free<T> {
	let val : T
	
	init(x : T) {
		self.val = x
	}
	
	private override func fold<R>(norm: Free<T> -> R, codense : Codensity<T> -> R) -> R {
		return norm(self)
	}
	

/// Monads" by Rúnar Óli Bjarnason ~( http://blog.higher-order.com/assets/trampolines.pdf ) with the
/// added benefit of Trampoline itself becoming a Monad.
public struct Trampoline<T> {
	private let t : FreeId<T>
	
	private init(_ t : FreeId<T>) {
		self.t = t
	}
	
