diff options
Diffstat (limited to '')
-rw-r--r-- | users/wpcarro/emacs/pkgs/bag/bag.el (renamed from users/wpcarro/emacs/.emacs.d/wpc/bag.el) | 58 |
1 files changed, 33 insertions, 25 deletions
diff --git a/users/wpcarro/emacs/.emacs.d/wpc/bag.el b/users/wpcarro/emacs/pkgs/bag/bag.el index 467e25fceb65..502f5672536e 100644 --- a/users/wpcarro/emacs/.emacs.d/wpc/bag.el +++ b/users/wpcarro/emacs/pkgs/bag/bag.el @@ -8,7 +8,7 @@ ;; 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 +;; of Sets is something that bags resemble, so multi-set isn't as bad of a name ;; as it may first seem. ;; ;; If you've used Python's collections.Counter, the concept of a bag should be @@ -27,7 +27,7 @@ ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; (require 'al) -(require 'number) +(require 'list) ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Library @@ -35,36 +35,44 @@ (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 (al-new))) -(defun bag-contains? (x xs) - "Return t if XS has X." - (al-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))))) + (list-reduce (bag-new) #'bag-add))) + +(defun bag-add (x xs) + "Add X to XS." + (if (bag-contains? x xs) + (struct-update + bag xs (lambda (xs) (al-update x (lambda (x) (+ 1 x)) xs)) xs) + (struct-update bag xs (lambda (xs) (al-set x 1 xs)) xs))) + +(defun bag-remove (x xs) + "Remove X from XS. +This is a no-op is X doesn't exist in XS." + (when (bag-contains? x xs) + (struct-update bag xs (lambda (xs) (al-delete x xs)) xs))) + +(defun bag-count (x xs) + "Return the number of occurrences of X in XS." + (al-get x (bag-xs xs) 0)) + +(defun bag-total (xs) + "Return the total number of elements in XS." + (->> (bag-xs xs) + (al-reduce 0 (lambda (_key v acc) (+ acc v))))) + +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; +;; Predicates +;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; + +(defun bag-contains? (x xs) + "Return t if XS has X." + (al-has-key? x (bag-xs xs))) (provide 'bag) ;;; bag.el ends here |