A simple macro to aid with dealing with promise chains in ClojureScript

promise.cljc

(ns lilactown.promise)

;; This is a simple macro to aid with dealing with promise chains
;; in ClojureScript. Often external JS libraries (such as request-promise
;; or other async libs) return a promise object, so we write code like:
;;
;; (-> promise-value
;;    (.then do-something)
;;    (.then #(do-something-else %))
;;    (.then (fn [val] (and-again val)))
;;
;; With `promise->`, we can remove the .then and use it like any other threading macro:
;;
;; (promise-> promise-value
;;    do-something
;;    #(do-something-else %)
;;    (fn [val] (and-again val)))

(defmacro promise-> [promise & body]
  `(-> ~promise
        ~@(map (fn [expr] (list '.then expr)) body)))

(defmacro ->-> [value fun & body]
  `(-> ~promise
       ~@(map (fn [expr] (list fun expr)) body)))

(->-> promise-value .then
  do-something
  #(do-something-else %)
  (fn [val] (and-again val)))```