Comment by adityaathalye

Yeah, absent automatic TCO, we have to do it all, explicitly, by hand... `recur` and `trampoline`.

recur: https://clojuredocs.org/clojure.core/recur

  > Evaluates the exprs in order, then, in parallel, rebinds the bindings of

the recursion point to the values of the exprs.

  (def factorial
    (fn [n]
      (loop [cnt n
             acc 1]
         (if (zero? cnt)
              acc
            (recur (dec cnt) (* acc cnt))
  ; in loop cnt will take the value (dec cnt)
  ; and acc will take the value (* acc cnt)
  ))))

trampoline: https://clojuredocs.org/clojure.core/trampoline

  > trampoline can be used to convert algorithms requiring mutual recursion without stack consumption.

i.e. these emulate TCO, with similar stack consumption properties (they don't implement real TCO).

(edit: formatting)