Rework, use let and more idiomatic code

1 files changed, 29 insertions, 22 deletions

diff --git a/mathslap-rec/mathslap-rec.clisp b/mathslap-rec/mathslap-rec.clisp
index c09e3c2..86d607b 100644
--- a/mathslap-rec/mathslap-rec.clisp
+++ b/mathslap-rec/mathslap-rec.clisp
@@ -6,29 +6,36 @@
 (print "MathSlap")
 (print "Hit Enter for another number. q and Enter to quit.")
 
-(defparameter *line* "")
-(defparameter *out* "MathSlap ")
-(defparameter *random-state* 0)
 (setq *random-state* (make-random-state t))
 
+;;;; Generate a random number for our game. Avoid having to write the
+;;;; same code several times.
+(defun have-number ()
+  (+ (random 10) 1))
+
 ;;;; append string parameter with a random number 1 through 10 and a space
-(defun concat (o)
-  (concatenate 'string o (write-to-string (+ (random 10) 1)) " ")
-)
-
-(defun recloop (o)
-;;;; append o with a random number 1 through 10 and a space
-  (setq o (concat o))
-  (print o)
-;;;; wait for input
-  (setq *line* (read-line *standard-input*))
-  (if (string= *line* "q")(quit))
-  (recloop o)
-)
-
-;;;; Add numbers to output string. Comment one of these out to start with 2 numbers.
-(setq *out* (concat *out*))
-(setq *out* (concat *out*))
-;;;; recursive loop
-(recloop *out*)
+(defun extend-prompt (o)
+  (concatenate 'string o (write-to-string (have-number)) " "))
+
+;;;; Same but with format, possibly more readable?
+;; (defun extend-prompt (o)
+;;   (format nil "~a~d " o (have-number)))
+
+(defun recloop (o input)
+  ;; Only recurse if the input is not "q"
+  (unless (string= input "q")
+    ;; Deal with the current state: output the prompt
+    (print o)
+    (finish-output)
+    ;; Prepare the next prompt and collect input.
+    ;; Use a LET form to use local variables
+    (let ((prompt (extend-prompt o))
+	  (new-input (read-line *standard-input*)))
+      (recloop prompt new-input))))
+
 
+;;;; Initiate the recursion
+;; Use a LET* form for local variables, with defined variables depending on each other.
+(let* ((starting-numbers (list (have-number) (have-number)))
+       (starting-prompt (format nil "MathSlap ~{~a ~}" starting-numbers)))
+  (recloop starting-prompt nil))