useful-cljs-macros.clj

(defmacro amap-inplace-new
  "Maps an expression across an array a, using an index named idx, and
  element el:
  (amap-inplace [[idx el] arr]
     [idx el])"
  [[[idx el] arr] & body]
  `(let [a# ~arr]
     (dotimes [~idx (alength a#)]
       (let [~el (aget a# ~idx)]
         (aset a# ~idx (do ~@body))))))

(defmacro afor
  "Like for but eagerly builds a JS array.
  Usually for react consumption."
  [[item coll] & body]
  `(reduce (fn [neue# ~item]
             (.push neue# (do ~@body))
             neue#)
           (cljs.core/array) ~coll))

(defmacro set!!
  ([x v]
   (list 'js* "~{} = ~{}" x v))
  ([x a0 v]
   (list 'js* "~{} = ~{}" (list '.. x a0) v))
  ([x a0 a1 v]
   (list 'js* "~{} = ~{}" (list '.. x a0 a1) v))
  ([x a0 a1 a2 v]
   (list 'js* "~{} = ~{}" (list '.. x a0 a1 a2) v)))