Added lisp along with some study work

lisp/ansi_lisp/ch2/problem_8/print_dots.lisp

@@ -0,0 +1,26 @@
+;; Take a positive int and print that many dots
+
+;; repetition
+(defun print-dots(num-of-dots)
+	(do ((i 0 (+ i 1)))
+		((= i num-of-dots) 'done)
+		(format t ". ")))
+;; recursion
+(defun print-dots-rec(num-of-dots)
+	;plusp checks if it's a positivie integer above 0.0
+	(if (plusp num-of-dots)
+		(progn
+			(format t ". ")
+			(print-dots-rec(- num-of-dots 1)))))
+
+;; Take a list and return the number of times the symbol "a" occurs in it
+(defun count-a-symbols(lst)
+	(do ((new-lst lst (cdr new-lst))
+			 (n 0 (+ n (if (eq (car new-lst) 'a) 1 0))))
+		  ((not new-lst) n)))
+
+;; Now do a recursive version (which is probably easier)
+(defun count-a-symbols-rec(lst)
+  (if lst
+    (+ (if (eq (car lst) 'a)1 0) (count-a-symbols-rec(cdr lst)))
+    1))