Add more clojure functions in the examples

examples/utils.dst

@@ -16,10 +16,12 @@
     (++ n))
    reversed)
 
-
-(defn reverse [t]
+'(arrays are more efficient so reverse-tuple will not be used)
+(defn reverse
+  "Reverses order of give array or tuple"
+  [t]
   (def the-type (type t))
-  (cond (= the-type  :tuple) (reverse-tuple t)
+  (cond (= the-type :tuple) (->> t iter2array reverse-array (apply tuple) )
         (= the-type :array) (reverse-array t)))
 
 
@@ -30,6 +32,30 @@
          exp-1
          exp-2))
 
+(defmacro when-not
+"Sorthand for (if (not ... "
+  [condition exp-1]
+  (tuple 'when (tuple 'not condition) exp-1))
+
+
+(defmacro if-let
+  [bindings then else]
+  (def head (ast-unwrap1 bindings))
+  (tuple 'let head
+         (tuple 'if (get head 1)
+              then
+              else)))
+
+
+(defmacro when-let
+  [bindings & then]
+  (def head (ast-unwrap1 bindings))
+  (tuple 'let head
+      (tuple
+        'when
+        (get head 1)  (apply tuple (array-concat ['do] (ast-unwrap1 then)))  )))
+
+
 (defn comp0-
   "Compose two functions. Second function must accept only one argument)"
  [f g] (fn [x] (f (g x))))
@@ -51,6 +77,6 @@
     (do
       (def f (get functions 0))
       (def g (get  functions 1))
-     (apply comp  (comp0 f g) (array-slice functions  2 -1))) )))
+     (apply comp  (comp0- f g) (array-slice functions  2 -1))) )))