diff options
author | William Carroll <wpcarro@gmail.com> | 2019-10-09T11·13+0100 |
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committer | William Carroll <wpcarro@gmail.com> | 2019-12-24T15·21+0000 |
commit | 6b456c1b7a4f6899f063a6e65355af51901d9c7a (patch) | |
tree | cfc70d74818ae9fabdbbfb0cf16cce092e4c1a09 /configs/shared/.emacs.d/wpc/maybe.el | |
parent | a7c72adb2ebec1e497fc040eaf3551d564d61a5b (diff) |
Massive configuration overhaul
Currently paying the price of months of non-diligent git usage. Here's what has changed. - Theming support in Gvcci and wpgtk - Dropping support for i3 - Supporting EXWM - Many Elisp modules - Collapsed redundant directories in ./configs
Diffstat (limited to 'configs/shared/.emacs.d/wpc/maybe.el')
-rw-r--r-- | configs/shared/.emacs.d/wpc/maybe.el | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/configs/shared/.emacs.d/wpc/maybe.el b/configs/shared/.emacs.d/wpc/maybe.el new file mode 100644 index 000000000000..0973b1ed65f7 --- /dev/null +++ b/configs/shared/.emacs.d/wpc/maybe.el @@ -0,0 +1,102 @@ +;;; maybe.el --- Library for dealing with nil values -*- lexical-binding: t -*- +;; Author: William Carroll <wpcarro@gmail.com> + +;;; Commentary: +;; Inspired by Elm's Maybe library. +;; +;; For now, a Nothing value will be defined exclusively as a nil value. I'm +;; uninterested in supported falsiness in this module even at risk of going +;; against the LISP grain. +;; +;; I'm avoiding introducing a struct to handle the creation of Just and Nothing +;; variants of Maybe. Perhaps this is a mistake in which case this file would +;; be more aptly named nil.el. I may change that. Because of this limitation, +;; functions in Elm's Maybe library like andThen, which is the monadic bind for +;; the Maybe type, doesn't have a home here since we cannot compose multiple +;; Nothing or Just values without a struct or some other construct. +;; +;; Possible names for the variants of a Maybe. +;; None | Some +;; Nothing | Something +;; None | Just +;; Nil | Set +;; +;; NOTE: In Elisp, values like '() (i.e. the empty list) are aliases for nil. +;; What else in Elisp is an alias in this way? +;; Examples: +;; TODO: Provide examples of other nil types in Elisp. + +;;; Code: + +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +;; Dependencies +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; + +(require 'prelude) +(require 'list) + +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +;; Constants +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; + +(defvar maybe/test? t + "When t, run the test suite defined herein.") + +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +;; Library +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; + +(defun maybe/nil? (x) + "Return t if X is nil." + (eq nil x)) + +(defun maybe/some? (x) + "Return t when X is non-nil." + (not (maybe/nil? x))) + +(defun maybe/nils? (&rest xs) + "Return t if all XS are nil." + (list/all? #'maybe/nil? xs)) + +(defun maybe/somes? (&rest xs) + "Return t if all XS are non-nil." + (list/all? #'maybe/some? xs)) + +(defun maybe/default (default x) + "Return DEFAULT when X is nil." + (if (maybe/nil? x) default x)) + +(defun maybe/map (f x) + "Apply F to X if X is not nil." + (if (maybe/some? x) + (funcall f x) + x)) + +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +;; Tests +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; + +(when maybe/test? + ;; nil? + (prelude/assert (maybe/nil? nil)) + (prelude/refute (maybe/nil? t)) + ;; some? + (prelude/assert (maybe/some? 10)) + (prelude/refute (maybe/some? nil)) + ;; nils? + (prelude/assert (maybe/nils? nil nil nil nil)) + (prelude/refute (maybe/nils? nil t nil t)) + ;; somes? + (prelude/assert (maybe/somes? t 10 '(1 2 3) "some")) + (prelude/refute (maybe/somes? t nil '(1 2 3) "some")) + ;; default + (prelude/assert + (and (= 0 (maybe/default 5 0)) + (= 5 (maybe/default 5 nil)))) + ;; map + (prelude/assert + (and (= 2 (maybe/map #'1+ 1)) + (eq nil (maybe/map #'1+ nil))))) + +(provide 'maybe) +;;; maybe.el ends here |