let-pipeline.clj

(defmacro let-pipeline [decls & body]
  (let [pairs (partition 2 decls)
        vars (map first pairs)
        exprs (map second pairs)
        predecessors (map #(take % vars) (range (count vars)))]
    `(let [~@(mapcat
               (fn [v preds expr]
                 `[~v
                   (run-pipeline (merge-results ~@preds)
                     (fn [[~@preds]] ~expr))])
               vars
               predecessors
               exprs)]
       (run-pipeline (merge-results ~@vars)
         (fn [[~@vars]]
           ~@body)))))