Merge pull request #6 from FrizzBolt/03-lists

Add solutions to section 03-lists

03_lists.clj

@@ -1,42 +1,48 @@
 
   ; "Lists can be expressed by function or a quoted form"
-  (= '(__ __ __ __ __) (list 1 2 3 4 5))
+  (= '(1 2 3 4 5) (list 1 2 3 4 5))
 
   ; "They are Clojure seqs (sequences), so they allow access to the first"
-  (= __ (first '(1 2 3 4 5)))
+  (= 1 (first '(1 2 3 4 5)))
 
   ; "As well as the rest"
-  (= __ (rest '(1 2 3 4 5)))
+  (= 2 3 4 5 (rest '(1 2 3 4 5))) ;; J -
 
   ; "Count your blessings"
-  (= __ (count '(dracula dooku chocula)))
+  (= 3 (count '(dracula dooku chocula)))
 
   ; "Before they are gone"
-  (= __ (count '()))
+  (= 0 (count '()))
 
   ; "The rest, when nothing is left, is empty"
-  (= __ (rest '(100)))
+  (=  (rest '(100))) ;; J - returns nothing.
 
   ; "Construction by adding an element to the front is easy"
-  (= __ (cons :a '(:b :c :d :e)))
+  (= :a :b :c :d :e (cons :a '(:b :c :d :e))) ;; J - cons add's the element on the left to the beginning
+                                              ;; of the list on the right and returns a seq.
+                                              ;;(EX: (cons [1 2] '(3 4 5)) => '([1 2] 3 4 5)
 
   ; "Conjoining an element to a list isn't hard either"
-  (= __ (conj '(:a :b :c :d) :e))
+  (= :a :b :c :d :e (conj '(:a :b :c :d) :e))
+                                  ;; J - conj works like cons, but takes any number of arguments from
+                                  ;; the right and adds them to the beginning of the list on the left
+                                  ;; returning them in the structure of whatever the list on the left is defined
+                                  ;; as originally. (EX: (conj [4 5 6] 1 2 3) => [1 2 3 4 5 6]
 
   ; "You can use a list like a stack to get the first element"
-  (= __ (peek '(:a :b :c :d :e)))
+  (= :a (peek '(:a :b :c :d :e))) ;; J - returns the first element
 
   ; "Or the others"
-  (= __ (pop '(:a :b :c :d :e)))
+  (= (:b) (pop '(:a :b :c :d :e))) ;; J - pops the first element and returns the others as a seq
 
   ; "But watch out if you try to pop nothing"
-  (= __ (try
+  (=  (try ;; J - Catch raises an error similar to 'raise' in Ruby.
           (pop '())
           (catch IllegalStateException e
             "No dice!")))
 
   ; "The rest of nothing isn't so strict"
-  (= __ (try
+  (= () (try
           (rest '())
           (catch IllegalStateException e
             "No dice!")))