#lang racket
(require "stream-base.rkt")

; implicit streams - defined as a least fixed-point, that is the 
; smallest set satisfying the equations.

; the stream of 1 1 1 1 1 ...
(define ones (s-cons 1 ones))

; try 
; (print ones)
; (s-ref ones 100)
; (print ones)

; add the two streams offset by 1 position and you get fibonacci
(define fibs-imp
  (s-cons 0 (s-cons 1 (s-map + (s-rest fibs-imp) fibs-imp))))

; try 
; (print fibs-imp)
; (s-ref fibs-imp 3)
; (print fibs-imp)