@@ -4,7 +4,9 @@ This library provides a language for expressing data manipulations as

 the composition of more primitive operations.

 #+BEGIN_SRC lisp

-  DATA-LENS> (funcall (on (compress-runs :collector 'combine-matching-lists)

+  DATA-LENS> (funcall (on (alexandria:compose

+                           (over (transform-tail (over (slice 1))))

+                           (compress-runs :collector 'combine-matching-lists))

                           (alexandria:compose 

                            (over (data-lens:juxt

                                   (data-lens:element 0)

@@ -102,6 +102,15 @@

   (lambda (seq)

     (map 'list selector seq)))

+(defun slice (start &optional end)

+  (lambda (it)

+    (subseq it start end)))

+

+(defun-ct transform-tail (fun)

+  (lambda (it)

+    (list* (car it)

+           (funcall fun (cdr it)))))

+

 (defun-ct key-transform (fun key-get key-set)

   (lambda (it)

     (let ((key-val (funcall key-get it)))