From fb6e1607ca7741a2109c372cb01ae65d99fde3f7 Mon Sep 17 00:00:00 2001
From: Chouser <chouser@n01se.net>
Date: Fri, 17 Oct 2008 21:34:54 +0000
Subject: Add combinations to lazy-seqs

---
 src/clojure/contrib/lazy_seqs/lazy_seqs.clj | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'src')

diff --git a/src/clojure/contrib/lazy_seqs/lazy_seqs.clj b/src/clojure/contrib/lazy_seqs/lazy_seqs.clj
index 17fe1a69..429700de 100644
--- a/src/clojure/contrib/lazy_seqs/lazy_seqs.clj
+++ b/src/clojure/contrib/lazy_seqs/lazy_seqs.clj
@@ -86,3 +86,14 @@
        (map #(cons f %) (permutations r)))
      (rotations x))
     (list nil)))
+
+(defn combinations
+  "Returns a lazy seq of all combinations built of one item from each seq given.
+   See also (doc for)"
+  [& acs]
+  (let [step (fn step [head [s & cs :as acs]]
+               (if acs
+                 (mapcat #(step (conj head %) cs) s)
+                 (list head)))]
+    (when acs
+      (step [] acs))))
-- 
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