->> and -> asymmetries

asym.clj

;; cond-> inside -> is fine
(-> input
  (dothis ...)
  (cond-> test (maybe do this also ...))
  (dothat ...))
  
;; cond->> inside ->> isn't fine
(->> input
  (dothis ...)
  (cond->> test (maybe do this also ...)) ; the input seq comes last because of ->> but cond->> expects it first.
  (dothat ...))

;; cond->>> ?
(defmacro cond->>> [& forms+expr]
  `(cond->> ~(last forms+expr) ~@(butlast forms+expr)))

;; A bit in the same vein: you can nest ->> inside -> but not the other way round