add exercices 24 / 25 / 26

Author: Raphaël Squelbut

src/structured_data.clj

@@ -87,7 +87,7 @@
   (or (apply <= a-seq) (apply >= a-seq)))
 
 (defn toggle [a-set elem]
-  (if (contains? a-set elem )
+  (if (contains? a-set elem)
     (disj a-set elem)
     (conj a-set elem)))
 
@@ -103,13 +103,16 @@
   (contains? (:authors book) author))
 
 (defn authors [books]
-  :-)
+  (set (apply concat (map :authors books))))
 
 (defn all-author-names [books]
-  :-)
+  (set (map :name (authors books))))
 
 (defn author->string [author]
-  :-)
+  (let [life-info
+        (fn [author] (if (or (:birth-year author) (:death-year author))
+                       (str " (" (:birth-year author) " - " (:death-year author) ")")))]
+    (apply str (:name author) (life-info author))))
 
 (defn authors->string [authors]
   :-)
@@ -137,4 +140,17 @@
 
 ; %________%
 (comment
-  (print "coucou"))
+  (def china {:name "China Miéville", :birth-year 1972})
+  (def octavia {:name       "Octavia E. Butler"
+                :birth-year 1947
+                :death-year 2006})
+  (def friedman {:name "Daniel Friedman" :birth-year 1944})
+  (def felleisen {:name "Matthias Felleisen"})
+
+  (def cities {:title "The City and the City" :authors #{china}})
+  (def wild-seed {:title "Wild Seed", :authors #{octavia}})
+  (def embassytown {:title "Embassytown", :authors #{china}})
+  (def little-schemer {:title   "The Little Schemer"
+                       :authors #{friedman, felleisen}})
+
+  (def books [cities, wild-seed, embassytown, little-schemer]))