Chapter 4, Metalinguistic Abstraction
I implemented a simple example which shows the difference between streams and lazier lazy lists, the example just demostrates that even ‘car’ is not evaluated unless it is accessed.
1 2 3 4 5 6 7 1 ]=> (define test (lambda() (display 'invoked) 1)) ;Value: test 1 ]=> (cons-stream (test) (test)) invoked ;Value 76: (1 . #[compound-procedure 77])
1 2 3 4 5 6 7 8 9 10 11 ;;; L-Eval input: (define test (lambda() (display 'invoked) 1)) ;;; L-Eval value: ok ;;; L-Eval input: (cons (test) (test)) ;;; L-Eval value: (compound-procedure (m) ((m x y)) <procedure-env>)
Take advantage of extra laziness
First, I thought of infinite lists in both directions but soon realised that this can be done with streams too. Similarly we can implement infinite trees too using streams(hint: cons of cons).
So, the only case where I found that extra laziness is giving extra advantage is circular dependencies which in the text is already demonstrated for solving first order differential equations.