Lesson completed, all 131 checks passed. Long nice exercise.

.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:

project.clj

@@ -1,5 +1,5 @@
 (defproject structured-data "1.0.0-SNAPSHOT"
-  :dependencies [[org.clojure/clojure "1.5.1"]
+  :dependencies [[org.clojure/clojure "1.8.0"]
                  [iloveponies.tests/structured-data "0.1.0-SNAPSHOT"]]
   :profiles {:dev {:plugins [[lein-midje "3.1.1"]]}})
 

src/structured_data.clj

@@ -1,114 +1,280 @@
 (ns structured-data)
 
 (defn do-a-thing [x]
-  :-)
+  (let [x2 (+ x x)]
+    (Math/pow x2 x2)))
 
 (defn spiff [v]
-  :-)
+  (let [sz (count v)]
+    (cond
+      (>= sz 3) (+ (get v 0) (get v 2))
+      (>= sz 1) (get v 0)
+      :else nil)))
 
 (defn cutify [v]
-  :-)
+  (conj v "<3"))
 
-(defn spiff-destructuring [v]
-  :-)
+(defn spiff-destructuring [[x0 x1 x2]]
+  (cond
+    (not (= x2 nil)) (+ x0 x2)
+    (not (= x0 nil)) (x0)
+    :else nil))
 
 (defn point [x y]
   [x y])
 
+
 (defn rectangle [bottom-left top-right]
   [bottom-left top-right])
 
+
 (defn width [rectangle]
-  :-)
+  (let [[[x1 y1] [x2 y2]] rectangle]
+    (- x2 x1)))
 
 (defn height [rectangle]
-  :-)
+  (let [[[x1 y1] [x2 y2]] rectangle]
+    (- y2 y1)))
 
 (defn square? [rectangle]
-  :-)
+  (let [[bottom-left up-right] rectangle]
+    (let [w (width [bottom-left up-right])
+          h (height [bottom-left up-right])]
+      (if (= h w)
+        true
+        false))))
 
 (defn area [rectangle]
-  :-)
+  (* (width rectangle) (height rectangle)))
 
 (defn contains-point? [rectangle point]
-  :-)
+  (let [[[x1 y1] [x2 y2]] rectangle
+        [x0 y0] point]
+    (if (and (<= x1 x0 x2) (<= y1 y0 y2))
+      true
+      false)))
 
 (defn contains-rectangle? [outer inner]
-  :-)
+  (let [[inner-lower-left inner-up-right] inner]
+    (if (and (contains-point? outer inner-lower-left)
+             (contains-point? outer inner-up-right))
+      true
+      false)))
 
 (defn title-length [book]
-  :-)
+  (count (:title book)))
 
 (defn author-count [book]
-  :-)
+  (count (:authors book)))
 
 (defn multiple-authors? [book]
-  :-)
+  (if (< 1 (author-count book))
+    true
+    false))
 
 (defn add-author [book new-author]
-  :-)
+  (assoc book :authors (conj (:authors book) new-author)))
 
 (defn alive? [author]
-  :-)
+  (if (contains? author :death-year)
+    false
+    true))
 
 (defn element-lengths [collection]
-  :-)
+  (map count collection))
 
 (defn second-elements [collection]
-  :-)
+  (let [second
+        (fn [x] 
+          (let [[x1 x2] x]
+            x2))]
+    (map second collection)))
 
 (defn titles [books]
-  :-)
+  (map :title books))
 
 (defn monotonic? [a-seq]
-  :-)
+  (cond
+    (apply <= a-seq) true
+    (apply >= a-seq) true
+    :else false)) 
 
 (defn stars [n]
-  :-)
+  (apply str (repeat n \*)))
 
 (defn toggle [a-set elem]
-  :-)
+  (if (contains? a-set elem)
+    (disj a-set elem)
+    (conj a-set elem)))
 
 (defn contains-duplicates? [a-seq]
-  :-)
+  (let [nr (count a-seq)]
+    (let [nr-unique (count (set a-seq))]
+      (if (> nr nr-unique)
+        true
+        false))))
+
+(defn old-book->new-book [book]
+  (assoc book :authors (set (:authors book))))
+
+(defn has-author? [book author]
+  (contains? (:authors book) author))
+
+(defn authors [books]
+  (let [authors-book
+        (fn [book]
+          (:authors book))]
+    (apply clojure.set/union (map authors-book books))))
+
+(defn all-author-names [books]
+  (set  (map :name (authors books))))
+
+(defn author->string [author]
+  (let [author-name (:name author)]
+    (let [birth-year (:birth-year author)]
+      (let [death-year (:death-year author)]
+        (cond
+          (and birth-year death-year) (str author-name " (" birth-year " - " death-year \))
+          birth-year (str author-name " (" birth-year " - )")
+          :else (str author-name)
+          )))))
+
+(defn authors->string [authors]
+  (let [print-author
+        (fn [author] (author->string author))]
+    (apply str (interpose ", " (map print-author authors)))))
+
+(defn book->string [book]
+  (str (:title book) ", written by " (authors->string (:authors book))))
+
+(defn books->string [books]
+  (cond
+    (= 0 (count books)) (str "No books.")
+    (= 1 (count books)) (str "1 book. " (apply book->string books) ".")
+    :else (let [each-book
+                (fn [book] (book->string book))]
+            (apply str (count books) " books. " (apply str (map each-book books)) "."))))
+(defn old-book->new-book [book]
+  (assoc book :authors (set (:authors book))))
+
+(defn has-author? [book author]
+  (contains? (:authors book) author))
+
+(defn authors [books]
+  (let [authors-book
+        (fn [book]
+          (:authors book))]
+    (apply clojure.set/union (map authors-book books))))
+
+(defn all-author-names [books]
+  (set  (map :name (authors books))))
+
+(defn author->string [author]
+  (let [author-name (:name author)]
+    (let [birth-year (:birth-year author)]
+      (let [death-year (:death-year author)]
+        (cond
+          (and birth-year death-year) (str author-name " (" birth-year " - " death-year \))
+          birth-year (str author-name " (" birth-year " - )")
+          :else (str author-name)
+          )))))
+
+(defn authors->string [authors]
+  (let [print-author
+        (fn [author] (author->string author))]
+    (apply str (interpose ", " (map print-author authors)))))
+
+(defn book->string [book]
+  (str (:title book) ", written by " (authors->string (:authors book))))
 
+(defn books->string [books]
+  (cond
+    (= 0 (count books)) (str "No books.")
+    (= 1 (count books)) (str "1 book. " (apply book->string books) ".")
+    :else (let [each-book
+                (fn [book] (book->string book))]
+            (apply str (count books) " books. " (apply str (map each-book books)) "."))))
 (defn old-book->new-book [book]
-  :-)
+  (assoc book :authors (set (:authors book))))
 
 (defn has-author? [book author]
-  :-)
+  (contains? (:authors book) author))
 
 (defn authors [books]
-  :-)
+  (let [authors-book
+        (fn [book]
+          (:authors book))]
+    (apply clojure.set/union (map authors-book books))))
 
 (defn all-author-names [books]
-  :-)
+  (set  (map :name (authors books))))
 
 (defn author->string [author]
-  :-)
+  (let [author-name (:name author)]
+    (let [birth-year (:birth-year author)]
+      (let [death-year (:death-year author)]
+        (cond
+          (and birth-year death-year) (str author-name " (" birth-year " - " death-year \))
+          birth-year (str author-name " (" birth-year " - )")
+          :else (str author-name)
+          )))))
 
 (defn authors->string [authors]
-  :-)
+  (let [print-author
+        (fn [author] (author->string author))]
+    (apply str (interpose ", " (map print-author authors)))))
 
 (defn book->string [book]
-  :-)
+  (str (:title book) ", written by " (authors->string (:authors book))))
 
 (defn books->string [books]
-  :-)
+  (cond
+    (= 0 (count books)) (str "No books.")
+    (= 1 (count books)) (str "1 book. " (apply book->string books) ".")
+    :else (let [each-book
+                (fn [book] (book->string book))]
+            (str (count books) " books. " (apply str (interpose ". " (map each-book books))) "."))))
+
+(defn books-by-author [author books]
+  (filter (fn  [book] (has-author? book author)) books))
+
+(defn author-by-name [name authors]
+  (first (filter (fn [author] (= (:name author) name)) authors)))
+
+(defn living-authors [authors]
+  (filter (fn [author] (alive? author)) authors))
+
+(defn has-a-living-author? [book]
+  (let [authors (:authors book)]
+    (not (empty? (living-authors authors)))))
+
+(defn books-by-author [author books]
+  (filter (fn  [book] (has-author? book author)) books))
+
+(defn author-by-name [name authors]
+  (first (filter (fn [author] (= (:name author) name)) authors)))
+
+(defn living-authors [authors]
+  (filter (fn [author] (alive? author)) authors))
+
+(defn has-a-living-author? [book]
+  (let [authors (:authors book)]
+    (not (empty? (living-authors authors)))))
 
 (defn books-by-author [author books]
-  :-)
+  (filter (fn  [book] (has-author? book author)) books))
 
 (defn author-by-name [name authors]
-  :-)
+  (first (filter (fn [author] (= (:name author) name)) authors)))
 
 (defn living-authors [authors]
-  :-)
+  (filter (fn [author] (alive? author)) authors))
 
 (defn has-a-living-author? [book]
-  :-)
+  (let [authors (:authors book)]
+    (not (empty? (living-authors authors)))))
 
 (defn books-by-living-authors [books]
-  :-)
+  (filter (fn [book] (has-a-living-author? book)) books))
 
 ; %________%