diff --git a/.travis.yml b/.travis.yml
index 455f3c0..45c29f6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: clojure
-lein: lein2
-script: lein2 midje :config .midje-grading-config.clj
+lein: lein
+script: lein midje :config .midje-grading-config.clj
 jdk:
   - openjdk7
 notifications:
diff --git a/src/recursion.clj b/src/recursion.clj
index 95d77aa..27deb43 100644
--- a/src/recursion.clj
+++ b/src/recursion.clj
@@ -1,92 +1,171 @@
 (ns recursion)
 
 (defn product [coll]
-  :-)
+  (if (empty? coll)
+    1
+    (* (first coll)
+       (product (rest coll)))))
 
 (defn singleton? [coll]
-  :-)
+  (and (not (empty? coll)) (empty? (rest coll))))
 
 (defn my-last [coll]
-  :-)
+  (if (or (singleton? coll) (empty? coll))
+    (first coll)
+    (my-last (rest coll))))
 
 (defn max-element [a-seq]
-  :-)
+  (let [first-of-seq (first a-seq)]
+    (if (or (singleton? a-seq) (empty? a-seq))
+      first-of-seq
+      (max first-of-seq (max-element (rest a-seq))))))
 
 (defn seq-max [seq-1 seq-2]
-  [:-])
+  (if (<= (count seq-1) (count seq-2))
+    seq-2
+    seq-1))
 
 (defn longest-sequence [a-seq]
-  [:-])
+  (if (empty? a-seq)
+    nil
+    (seq-max (first a-seq) (longest-sequence (rest a-seq)))))
 
 (defn my-filter [pred? a-seq]
-  [:-])
+  (let [first (first a-seq)
+        rest (rest a-seq)]
+  (cond 
+    (empty? a-seq) a-seq
+    (pred? first)
+      (cons first (my-filter pred? rest))
+    :else (my-filter pred? rest))))
 
 (defn sequence-contains? [elem a-seq]
-  :-)
+  (cond
+   (empty? a-seq) false                       
+   (= (first a-seq) elem) true
+   :else (sequence-contains? elem (rest a-seq))))
 
 (defn my-take-while [pred? a-seq]
-  [:-])
+  (let [first (first a-seq)]
+  (cond
+   (empty? a-seq) ()                       
+   (not (pred? first)) ()
+   :else (cons first (my-take-while pred? (rest a-seq))))))
 
 (defn my-drop-while [pred? a-seq]
-  [:-])
+  (cond
+   (empty? a-seq) ()                       
+   (not (pred? (first a-seq))) a-seq
+   :else (my-drop-while pred? (rest a-seq))))
 
 (defn seq= [a-seq b-seq]
-  :-)
+  (cond
+    (and (empty? a-seq) (empty? b-seq)) true
+    (or
+      (empty? a-seq)
+      (empty? b-seq)
+      (not (= (first a-seq) (first b-seq)))) false 
+    :else (seq= (rest a-seq) (rest b-seq))))
 
 (defn my-map [f seq-1 seq-2]
-  [:-])
+  (if (or (empty? seq-1) (empty? seq-2))
+    ()
+    (cons (f (first seq-1) (first seq-2))
+          (my-map f (rest seq-1) (rest seq-2)))))
 
 (defn power [n k]
-  :-)
+  (if (zero? k)
+    1
+    (* n (power n (dec k)))))
 
 (defn fib [n]
-  :-)
+  (cond
+    (== n 0) 0
+    (== n 1) 1
+    :else (+ (fib (dec n)) (fib (- n 2)))))
 
 (defn my-repeat [how-many-times what-to-repeat]
-  [:-])
+  (if (<= how-many-times 0)
+    ()
+    (cons what-to-repeat
+          (my-repeat (dec how-many-times) what-to-repeat))))
 
 (defn my-range [up-to]
-  [:-])
+  (if (== up-to 0)
+    ()
+    (cons (dec up-to) (my-range (dec up-to)))))
 
 (defn tails [a-seq]
-  [:-])
+  (if (empty? a-seq)
+    '(())
+    (cons (seq a-seq) (tails (rest a-seq)))))
 
 (defn inits [a-seq]
-  [:-])
+  (reverse (map reverse (tails (reverse a-seq)))))
 
 (defn rotations [a-seq]
-  [:-])
+  (if (empty? a-seq)
+    '(())
+    (rest (map concat (tails a-seq) (inits a-seq)))))
 
 (defn my-frequencies-helper [freqs a-seq]
-  [:-])
+  (if (empty? a-seq)
+    freqs
+    (let [first (first a-seq)
+          freq (if (contains? freqs first)
+                (inc (get freqs first))
+                1)]
+      (my-frequencies-helper (assoc freqs first freq)
+                             (rest a-seq)))))
 
 (defn my-frequencies [a-seq]
-  [:-])
+  (my-frequencies-helper {} a-seq))
+
+(defn un-frequencies-helper [un-freqs a-map]
+  (if (empty? a-map)
+    un-freqs
+    (let [first (first a-map)
+          repeated (repeat (val first) (key first))]
+      (un-frequencies-helper (concat un-freqs repeated) (rest a-map)))))
 
 (defn un-frequencies [a-map]
-  [:-])
+  (un-frequencies-helper () a-map))
 
 (defn my-take [n coll]
-  [:-])
+  (if (or (empty? coll) (zero? n))
+    ()
+    (cons (first coll) (my-take (dec n) (rest coll)))))
 
 (defn my-drop [n coll]
-  [:-])
+  (if (or (empty? coll) (zero? n))
+    coll
+    (my-drop (dec n) (rest coll))))
 
 (defn halve [a-seq]
-  [:-])
+  (let [half (int (/ (count a-seq) 2))]
+    [(my-take half a-seq) (my-drop half a-seq)]))
 
 (defn seq-merge [a-seq b-seq]
-  [:-])
+    (cond 
+      (empty? a-seq) b-seq
+      (empty? b-seq) a-seq
+      :else (let [a-first (first a-seq)
+                  b-first (first b-seq)]
+              (if (< a-first b-first)
+                (cons a-first (seq-merge (rest a-seq) b-seq))
+                (cons b-first (seq-merge a-seq (rest b-seq)))))))
 
 (defn merge-sort [a-seq]
-  [:-])
+  (if (or (empty? a-seq) (singleton? a-seq))
+    a-seq
+    (let [[first second] (halve a-seq)]
+      (seq-merge (merge-sort first) (merge-sort second)))))
 
 (defn split-into-monotonics [a-seq]
-  [:-])
+  )
 
 (defn permutations [a-set]
-  [:-])
+  )
 
 (defn powerset [a-set]
-  [:-])
-
+  )