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-rw-r--r--examples.lisp31
1 files changed, 30 insertions, 1 deletions
diff --git a/examples.lisp b/examples.lisp
index 221c78e..df50a23 100644
--- a/examples.lisp
+++ b/examples.lisp
@@ -118,4 +118,33 @@ vector VEC, one at a time."
(zip! (range) (file-lines file))))
-;; find all export expressions in my bashrc file
+
+;;; Silly Scrambler ;;;
+
+
+(defun pad (str len &optional (pad-char #\Space]))
+ (let ((i 0))
+ (with-output-to-string (out)
+ (loop :for c :across str :do (incf i) (princ c out))
+ (loop :while (< i len) :do (incf i) (princ pad-char out)))))
+
+(defun scramble (n str)
+ (assert (< n (length str)))
+ (let ((str (pad str (* n (ceiling (/ (length str) n))))))
+ (concatenate 'string
+ (apply #'nconc
+ (mapcar #'collect
+ (disperse! n (seq str)))))))
+
+(defun chunk (n str)
+ (assert (zerop (mod (length str) n)))
+ (let ((size (/ (length str) n)))
+ (loop
+ :for i :below (length str) :by size
+ :collect (subseq str i (+ i size)) )))
+
+(defun descramble (n str)
+ (concatenate 'string
+ (collect
+ (apply #'intersperse!
+ (mapcar #'seq (chunk n str))))))