diff options
author | William Carroll <wpcarro@gmail.com> | 2019-10-09T11·13+0100 |
---|---|---|
committer | William Carroll <wpcarro@gmail.com> | 2019-12-24T15·21+0000 |
commit | 6b456c1b7a4f6899f063a6e65355af51901d9c7a (patch) | |
tree | cfc70d74818ae9fabdbbfb0cf16cce092e4c1a09 /configs/shared/.emacs.d/wpc/bag.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/bag.el')
-rw-r--r-- | configs/shared/.emacs.d/wpc/bag.el | 66 |
1 files changed, 66 insertions, 0 deletions
diff --git a/configs/shared/.emacs.d/wpc/bag.el b/configs/shared/.emacs.d/wpc/bag.el new file mode 100644 index 000000000000..c9511b18e737 --- /dev/null +++ b/configs/shared/.emacs.d/wpc/bag.el @@ -0,0 +1,66 @@ +;;; bag.el --- Working with bags (aka multi-sets) -*- lexical-binding: t -*- +;; Author: William Carroll <wpcarro@gmail.com> + +;;; Commentary: +;; What is a bag? A bag should be thought of as a frequency table. It's a way +;; to convert a list of something into a set that allows duplicates. Isn't +;; allowing duplicates the whole thing with Sets? Kind of. But the interface +;; of Sets is something that bags resemble, so multi-set isn't as bag of a name +;; as it may first seem. +;; +;; If you've used Python's collections.Counter, the concept of a bag should be +;; familiar already. +;; +;; Interface: +;; - add :: x -> Bag(x) -> Bag(x) +;; - remove :: x -> Bag(x) -> Bag(x) +;; - union :: Bag(x) -> Bag(x) -> Bag(x) +;; - difference :: Bag(x) -> Bag(x) -> Bag(x) + +;;; Code: + +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +;; Dependencies +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; + +(require 'number) + +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +;; Library +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; + +(cl-defstruct bag xs) + +(defun bag/update (f xs) + "Call F on alist in XS." + (let ((ys (bag-xs xs))) + (setf (bag-xs xs) (funcall f ys)))) + +(defun bag/new () + "Create an empty bag." + (make-bag :xs (alist/new))) + +(defun bag/contains? (x xs) + "Return t if XS has X." + (alist/has-key? x (bag-xs xs))) + +;; TODO: Tabling this for now since working with structs seems to be +;; disappointingly difficult. Where is `struct/update'? +;; (defun bag/add (x xs) +;; "Add X to XS.") + +;; TODO: What do we name delete vs. remove? +;; (defun bag/remove (x xs) +;; "Remove X from XS. +;; This is a no-op is X doesn't exist in XS.") + +(defun bag/from-list (xs) + "Map a list of `XS' into a bag." + (->> xs + (list/reduce + (bag/new) + (lambda (x acc) + (bag/add x 1 #'number/inc acc))))) + +(provide 'bag) +;;; bag.el ends here |