 		return undefined()
 	}
 	
-	func flatMap<B>(f : T -> Free<B>) -> Free<B> {
+	func flatMap<B>(f : T -> FreeId<B>) -> FreeId<B> {
 		return liftCodense(self, f)
 	}
 }
 
-private class Pure<T> : Free<T> {
+private class Pure<T> : FreeId<T> {
 	let val : T
 	
 	init(x : T) {
 		self.val = x
 	}
 	
-	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)
 	}
 	

}

/// There's got to be a better way to do this...
private func liftCodense<A, B>(a : Free<A>, k : A -> Free<B>) -> Codensity<B> {
	return Codensity<B>(sub: unsafeCoerce(a), unsafeCoerce(k))
}

private class Codensity<T> : Free<T> {
	let sub : Free<T>
	let k : T -> Free<T>
	
	private override func fold<R>(norm : Free<T> -> R, codense : Codensity<T> -> R) -> R {
		return codense(self)
	}
	
	init(sub : Free<T>, k : T -> Free<T>) {
		self.sub = sub
		self.k = k
	}
	
	private override func flatMap<B>(f: T -> Free<B>) -> Free<B> {
		return liftCodense(sub, { o in suspend(Trampoline(self.k(o).flatMap(f))).t })
	}
		

/// 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
	}
	
