From e5503751c4a3279055c4714a91c39affabb8c461 Mon Sep 17 00:00:00 2001 From: William Carroll Date: Fri, 5 Aug 2022 12:34:15 -0700 Subject: feat(wpcarro/emacs): Add fns to list.el new functions: - duplicate - last - delete - wrap also: - drop support for `list-head` (in favor of `list-first`) - add optional arg to first Change-Id: If3c48d4749a3bc5a853995996fa02a65a4076a10 Reviewed-on: https://cl.tvl.fyi/c/depot/+/6041 Reviewed-by: wpcarro Autosubmit: wpcarro Tested-by: BuildkiteCI --- users/wpcarro/emacs/pkgs/list/list.el | 40 ++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 8 deletions(-) (limited to 'users/wpcarro/emacs/pkgs/list/list.el') diff --git a/users/wpcarro/emacs/pkgs/list/list.el b/users/wpcarro/emacs/pkgs/list/list.el index 2aa226609d6e..a395eba2672e 100644 --- a/users/wpcarro/emacs/pkgs/list/list.el +++ b/users/wpcarro/emacs/pkgs/list/list.el @@ -68,6 +68,10 @@ "Joins `LISTS' into on list." (apply #'-concat lists)) +(defun list-duplicate (n x) + "Duplicates the given element, X, N times in a list." + (list-map (lambda (_) x) (number-sequence 1 n))) + (defun list-join (joint xs) "Join a list of strings, XS, with JOINT." (if (list-empty? xs) @@ -85,14 +89,17 @@ "Return the value in `XS' at `I', or nil." (nth i xs)) -(defun list-head (xs) - "Return the head of `XS'." - (car xs)) - -;; TODO: Learn how to write proper function aliases. -(defun list-first (xs) +(defun list-first (xs &optional default) "Alias for `list-head' for `XS'." - (list-head xs)) + (if (list-empty? xs) + default + (car xs))) + +(defun list-last (xs &optional default) + "Returns the last element in XS or DEFAULT if empty." + (if (list-empty? xs) + default + (nth (- (length xs) 1) xs))) (defun list-tail (xs) "Return the tail of `XS'." @@ -106,6 +113,17 @@ "Add `X' to the head of `XS'." (cons x xs)) +(defun list-delete (x xs) + "Deletes the given element, X, from XS. +Returns a new list without X. If X occurs more than once, only the first + occurrence is removed." + (let ((deleted? nil)) + (list-reject (lambda (y) + (if deleted? nil + (when (equal x y) + (setq deleted? t) t))) + xs))) + (defun list-filter (p xs) "Return a subset of XS where predicate P returned t." (list--assert-instance xs) @@ -202,13 +220,19 @@ Be leery of using this with things like alists. Many data structures in Elisp (defun list-contains? (x xs) "Return t if X is in XS using `equal'." (list--assert-instance xs) - (maybe-some? (seq-contains xs x))) + (maybe-some? (seq-contains-p xs x))) (defun list-xs-distinct-by? (f xs) "Return t if all elements in XS are distinct after applying F to each." (= (length xs) (set-count (set-from-list (list-map f xs))))) +(defun list-wrap (xs) + "Wraps XS in a list if it is not a list already." + (if (list-instance? xs) + xs + (list xs))) + ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ;; Helpers ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; -- cgit 1.4.1