Paths in a graph

gistfile1.clj

(defn paths
  "Returns a lazy sequence of path vectors from path [<start-node>] to
  target in graph."
  [graph target path]
  (let [this-node (peek path)]
    (if (= this-node target)
      [path]
      (->> (get graph this-node)
           (filter #(not-any? (fn [edge] (= edge [this-node %]))
                              (partition 2 1 path)))
           (mapcat #(paths graph target (conj path %)))))))

n01se.suxml> (paths '{a [b d], b [c], c [x], d [b]} 'x '[a])
([a b c x] [a d b c x])

n01se.suxml> (paths '{a [b a], b [c], c [x]} 'x '[a])
([a b c x] [a a b c x])

n01se.suxml> (paths '{a [b d], b [c], c [x]} 'x '[a])
([a b c x])

n01se.suxml> (paths '{a [b d], b [c], c [x], x [a x]} 'x '[a])
([a b c x])