flatteno

flatteno.clj

(defn list?o
  [v]
  (matche [v]
    ([[]] succeed)
    ([[_ . _]] succeed)))

(defn flatteno
  [in out]
  (matche [in]
    ([[]] (== out in))
    ([[?in-head . ?in-tail]]
     (fresh [prefix suffix]
       (flatteno ?in-tail suffix)
       (conde
         [(list?o ?in-head)     (flatteno ?in-head prefix) (appendo prefix suffix out)]
         ; here's my problem ...
         [(... somehow test not list?o here) (conso ?in-head suffix out)])))))