yin-yang problem.

yin-yang.scm

;; detailed continuation usage, see previous gist: https://gist.github.com/DadgadCafe/07b0b50bf9537522fed09b3dc8df2784

(define call/cc call-with-current-continuation)

(let* ((yin
         ((lambda (cc) (display #\@) cc)
          (call/cc (lambda (c) c))))
       (yang
         ((lambda (cc) (display #\*) cc)
          (call/cc (lambda (c) c)))))
    (yin yang))

;; yang catches previous yin
;; yin becomes previous yang

yinYang.js

'use strict'

// chain: ccYin -> yang -> cont -> ccYin(previous)
// obviously, Maximum call stack size exceeded
function makeYang (cont) {
  ccYin = yang

  function yang () {
    console.log('*')
    cont()
  }
}

function yin () {
  console.log('@')
  makeYang(ccYin)
  ccYin()
}

let ccYin = yin

ccYin()

call/cc is a black hole, terminates once it is applied with parameter.

(
  (
    (call/cc (lambda (k) k))
    (lambda (k) k)
  )
  "HEY!"
)

;; STEP 1: REPLACE k with
(lambda ? (
  (? (lambda (k) k)) "HEY!"
))

;; call/cc is proc take one parameter
;; REPLACE (call/cc (lambda (k) k)) with k
(
  (
    K
    (lambda (k) k)
  )
  "HEY!"
)
=>
(
  K
  (lambda (k) k)
)
;; RESULT
(
  (lambda ? (
    (? (lambda (k) k)) "HEY!"
  ))
  (lambda (k) k)
)
=>
(((lambda (k) k) (lambda (k) k)) "HEY!")
=>
((lambda (k) k) "HEY!")
=>
"HEY!"



(let ([x (call/cc (lambda (k) k))])
(x (lambda (ignore) "hi")))
=>
K:
(lambda ?
  (let ([x ?])
  (x (lambda (ignore) "hi"))))
=>
(let ([x K])
(x (lambda (ignore) "hi")))
=>
(K (lambda (ignore) "hi"))
=>
((lambda (ignore) "hi") (lambda (ignore) "hi"))
=>
"hi"