feat: add • compose operator

lens.lisp

@@ -234,7 +234,8 @@ contain the new value at the location focused by the lens."
            #:compress-runs #:combine-matching-lists #:sorted #:applicable-when
            #:of-length #:of-min-length #:of-max-length #:transform-head
            #:maximizing #:zipping #:applying #:splice-elt #:transform-elt #:denest
-           #:op #:defalias #:<> #:<>1))
+           #:op #:defalias #:<> #:<>1
+           #:•))
 (in-package :data-lens)
 
 
@@ -524,3 +525,5 @@ contain the new value at the location focused by the lens."
 
 (defmacro <>1 (&rest funs)
   `(alexandria:compose ,@funs))
+(defmacro • (&rest funs)
+  `(alexandria:compose ,@funs))

wrapped-sequence.lisp

@@ -0,0 +1,53 @@
+(defpackage :data-lens.wrapped-sequence
+  (:use :cl )
+  (:export ))
+(in-package :data-lens.wrapped-sequence)
+
+(defgeneric underlying (wrapper)
+  (:documentation "Return the underlying object of a wrapper"))
+
+(defclass tagged-sequence (standard-object sequence)
+  ((%underlying-sequence :initarg :underlying :accessor underlying)
+   (%key-fn :initarg :key :reader key)
+   (%invert-key :initarg :invert-key :reader invert-key)))
+
+(defmethod sb-sequence:length ((sequence tagged-sequence))
+  (length (underlying sequence)))
+
+(defmethod sb-sequence:elt ((sequence tagged-sequence) index)
+  (funcall (key sequence)
+           (elt (underlying sequence)
+                index)))
+
+(defmethod (setf sb-sequence:elt) (new-value (sequence tagged-sequence) index)
+  (setf (elt (underlying sequence)
+             index)
+        (funcall (invert-key sequence)
+                 (elt (underlying sequence)
+                      index)
+                 new-value)))
+
+(defmethod sb-sequence:adjust-sequence ((sequence tagged-sequence) length
+                                        &rest r
+                                        &key initial-element initial-contents)
+  (declare (ignore initial-element initial-contents))
+  (make-instance 'tagged-sequence
+                 :underlying (apply #'sb-sequence:adjust-sequence
+                                    (copy-seq (underlying sequence)) length
+                                    r)
+                 :key-fn (key sequence)
+                 :invert-key (invert-key sequence)))
+
+(defmethod sb-sequence:make-sequence-like
+    ((sequence tagged-sequence) length &rest r)
+  (apply #'sb-sequence:adjust-sequence sequence length r))
+
+(defun wrap-sequence (seq key-fn invert-key-fn)
+  (if invert-key-fn
+      (make-instance 'tagged-sequence
+                     :underlying seq
+                     :key key-fn
+                     :invert-key invert-key-fn)
+      (make-instance 'tagged-sequence
+                     :underlying seq
+                     :key key-fn)))