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+;;; dotted.el --- Working with dotted pairs in Elisp -*- lexical-binding: t -*-
+;; Author: William Carroll <wpcarro@gmail.com>
+
+;;; Commentary:
+;; Part of my primitives library extensions in Elisp.  Contrast my primitives
+;; with the wrapper extensions that I provide, which expose immutable variants
+;; of data structures like an list, alist, tuple, as well as quasi-typeclasses
+;; like sequence, etc.
+
+;;; Code:
+
+(require 'prelude)
+(require 'macros)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Library
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(cl-defun dotted/new (&optional a b)
+  "Create a new dotted pair (i.e. cons cell)."
+  (cons a b))
+
+(defun dotted/instance? (x)
+  "Return t if X is a dotted pair."
+  (let ((b (cdr x)))
+    (and b (atom b))))
+
+(defun dotted/first (x)
+  "Return the first element of X."
+  (car x))
+
+(defun dotted/second (x)
+  "Return the second element of X."
+  (cdr x))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Tests
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(progn
+  (prelude/assert
+   (equal '(fname . "Bob") (dotted/new 'fname "Bob")))
+  (prelude/assert
+   (dotted/instance? '(one . two)))
+  (prelude/refute
+   (dotted/instance? '(1 2 3))))
+
+(provide 'dotted)
+;;; dotted.el ends here