Simple graph compilation

graph_simple_compilation.clj

;; Functionally identical to (defn stats ...) above
(def stats (graph/eager-compile stats-graph)) 

(stats {:xs [1 2 3 6]})
; ==> {:n 4     
;      :m 3 
;      :m2 12.5 
;      :v 3.5) 

;; Result is error checked
(stats {:ys [1 2 3 6]})
; ==> (Exception. "Missing argument :xs ...")

;; Compilation is error checked too.
(graph/eager-compile 
  {:x (fnk [y] (inc y))
   :y (fnk [x] (dec x))})
; ==> (Exception. "Cannot compile cyclic graph 
                   (:x --> :y --> :x)")