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authorVincent Ambo <mail@tazj.in>2021-12-13T22·51+0300
committerVincent Ambo <mail@tazj.in>2021-12-13T23·15+0300
commit019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch)
tree76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/emacs/.emacs.d/wpc/dotted.el
parent464bbcb15c09813172c79820bcf526bb10cf4208 (diff)
parent6123e976928ca3d8d93f0b2006b10b5f659eb74d (diff)
subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226
git-subtree-dir: users/wpcarro
git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208
git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f
Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
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+;;; dotted.el --- Working with dotted pairs in Elisp -*- lexical-binding: t -*-
+
+;; Author: William Carroll <wpcarro@gmail.com>
+;; Version: 0.0.1
+;; URL: https://git.wpcarro.dev/wpcarro/briefcase
+;; Package-Requires: ((emacs "24.3"))
+
+;;; 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:
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Dependencies
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(require 'prelude)
+(require 'macros)
+(require 'cl-lib)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Library
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(cl-defun dotted-new (&optional a b)
+  "Create a new dotted pair of A and B."
+  (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