gistfile1.txt

(fn sleep [x] (: (io.popen (.. "sleep " (tostring x))) :close)) ;; simulate a slow process

(fn tick-producer []
  (coroutine.wrap
   (fn []
     (var i 0)
     (while (< i 10)
       (set i (+  1 i))
       (coroutine.yield i)
       (sleep 1)
       ))))

(let [ticks (tick-producer)]
  (accumulate [finished false
               t ticks
               &until finished]
    (do (print t)
        (= t 4)))
  (print "next" (ticks)))

gistfile2.txt

$ fennel foo.fnl 
1
2
3
4
 [... pauses ...]
next    6

;; this works, though, so I could just not use accumulate

(let [ticks (tick-producer)]
  (each [t ticks
         &until (matches? t)]
    (print t)))