#t and #f added to language, datetime fixes

stdlib/stdlib.lsp

@@ -1,5 +1,5 @@
 ; not a bool
-(defun not (x) (if x nil 1))
+(defun not (x) (if x nil #t))
 
 (defun is-pos? (n) (> n nil))
 (defun is-neg? (n) (< n nil))
@@ -70,13 +70,13 @@
 
         (while (and (< i lst_len) (= found_index -1))
             (if (= itm (index lst i))
-                (define found_index i)
-                (define i (+ i 1))
+                (set! found_index i)
+                (set! i (+ i 1))
                 ))
 
         ; TODO when nil will be implemented itm / nil
         (if (!= -1 found_index)
-            1
+            #t
             nil)
     ))