diff options
Diffstat (limited to 'users/wpcarro/emacs/.emacs.d/wpc/al.el')
-rw-r--r-- | users/wpcarro/emacs/.emacs.d/wpc/al.el | 254 |
1 files changed, 0 insertions, 254 deletions
diff --git a/users/wpcarro/emacs/.emacs.d/wpc/al.el b/users/wpcarro/emacs/.emacs.d/wpc/al.el deleted file mode 100644 index 3cf98fee296b..000000000000 --- a/users/wpcarro/emacs/.emacs.d/wpc/al.el +++ /dev/null @@ -1,254 +0,0 @@ -;;; al.el --- Interface for working with associative lists -*- lexical-binding: t -*- - -;; Author: William Carroll <wpcarro@gmail.com> -;; Version: 0.0.1 -;; Package-Requires: ((emacs "25.1")) - -;;; Commentary: -;; Firstly, a rant: -;; In most cases, I find Elisp's APIs to be confusing. There's a mixture of -;; overloaded functions that leak the implementation details (TODO: provide an -;; example of this.) of the abstract data type, which I find privileges those -;; "insiders" who spend disproportionately large amounts of time in Elisp land, -;; and other functions with little-to-no pattern about the order in which -;; arguments should be applied. In theory, however, most of these APIs could -;; and should be much simpler. This module represents a step in that direction. -;; -;; I'm modelling these APIs after Elixir's APIs. -;; -;; On my wishlist is to create protocols that will allow generic interfaces like -;; Enum protocols, etc. Would be nice to abstract over... -;; - associative lists (i.e. alists) -;; - property lists (i.e. plists) -;; - hash tables -;; ...with some dictionary or map-like interface. This will probably end up -;; being quite similar to the kv.el project but with differences at the API -;; layer. -;; -;; Similar libraries: -;; - map.el: Comes bundled with recent versions of Emacs. -;; - asoc.el: Helpers for working with alists. asoc.el is similar to alist.el -;; because it uses the "!" convention for signalling that a function mutates -;; the underlying data structure. -;; - ht.el: Hash table library. -;; - kv.el: Library for dealing with key-value collections. Note that map.el -;; has a similar typeclass because it works with lists, hash-tables, or -;; arrays. -;; - a.el: Clojure-inspired way of working with key-value data structures in -;; Elisp. Works with alists, hash-tables, and sometimes vectors. -;; -;; Some API design principles: -;; - The "noun" (i.e. alist) of the "verb" (i.e. function) comes last to improve -;; composability with the threading macro (i.e. `->>') and to improve consumers' -;; intuition with the APIs. Learn this once, know it always. -;; -;; - Every function avoids mutating the alist unless it ends with !. -;; -;; - CRUD operations will be named according to the following table: -;; - "create" *and* "set" -;; - "read" *and* "get" -;; - "update" -;; - "delete" *and* "remove" -;; -;; For better or worse, all of this code expects alists in the form of: -;; ((first-name . "William") (last-name . "Carroll")) -;; -;; Special thanks to github.com/alphapapa/emacs-package-dev-handbook for some of -;; the idiomatic ways to update alists. -;; -;; TODO: Include a section that compares alist.el to a.el from -;; github.com/plexus/a.el. - -;;; Code: - -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; -;; Dependencies: -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; - -(require 'macros) -(require 'dash) -(require 'tuple) -(require 'maybe) - -;; TODO: Support function aliases for: -;; - create/set -;; - read/get -;; - update -;; - delete/remove - -;; Support mutative variants of functions with an ! appendage to their name. - -;; Ensure that the same message about only updating the first occurrence of a -;; key is consistent throughout documentation using string interpolation or some -;; other mechanism. - -;; TODO: Consider wrapping all of this with `(cl-defstruct alist xs)'. - -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; -;; Constants -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; - -(defconst al-enable-tests? t - "When t, run the test suite.") - -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; -;; Library -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; - -;; TODO: Support a variadic version of this to easily construct alists. -(defun al-new () - "Return a new, empty alist." - '()) - -;; Create -;; TODO: See if this mutates. -(defun al-set (k v xs) - "Set K to V in XS." - (if (al-has-key? k xs) - (progn - ;; Note: this is intentional `alist-get' and not `al-get'. - (setf (alist-get k xs) v) - xs) - (list-cons `(,k . ,v) xs))) - -(defun al-set! (k v xs) - "Set K to V in XS mutatively. -Note that this doesn't append to the alist in the way that most alists handle - writing. If the k already exists in XS, it is overwritten." - (map-delete xs k) - (map-put! xs k v)) - -;; Read -(defun al-get (k xs) - "Return the value at K in XS; otherwise, return nil. -Returns the first occurrence of K in XS since alists support multiple entries." - (cdr (assoc k xs))) - -(defun al-get-entry (k xs) - "Return the first key-value pair at K in XS." - (assoc k xs)) - -;; Update -;; TODO: Add warning about only the first occurrence being updated in the -;; documentation. -(defun al-update (k f xs) - "Apply F to the value stored at K in XS. -If `K' is not in `XS', this function errors. Use `al-upsert' if you're -interested in inserting a value when a key doesn't already exist." - (if (not (al-has-key? k xs)) - (error "Refusing to update: key does not exist in alist") - (al-set k (funcall f (al-get k xs)) xs))) - -(defun al-update! (k f xs) - "Call F on the entry at K in XS. -Mutative variant of `al-update'." - (al-set! k (funcall f (al-get k xs))xs)) - -;; TODO: Support this. -(defun al-upsert (k v f xs) - "If K exists in `XS' call `F' on the value otherwise insert `V'." - (if (al-has-key? k xs) - (al-update k f xs) - (al-set k v xs))) - -;; Delete -;; TODO: Make sure `delete' and `remove' behave as advertised in the Elisp docs. -(defun al-delete (k xs) - "Deletes the entry of K from XS. -This only removes the first occurrence of K, since alists support multiple - key-value entries. See `al-delete-all' and `al-dedupe'." - (remove (assoc k xs) xs)) - -(defun al-delete! (k xs) - "Delete the entry of K from XS. -Mutative variant of `al-delete'." - (delete (assoc k xs) xs)) - -;; Additions to the CRUD API -;; TODO: Implement this function. -(defun al-dedupe-keys (xs) - "Remove the entries in XS where the keys are `equal'.") - -(defun al-dedupe-entries (xs) - "Remove the entries in XS where the key-value pair are `equal'." - (delete-dups xs)) - -(defun al-keys (xs) - "Return a list of the keys in XS." - (mapcar 'car xs)) - -(defun al-values (xs) - "Return a list of the values in XS." - (mapcar 'cdr xs)) - -(defun al-has-key? (k xs) - "Return t if XS has a key `equal' to K." - (maybe-some? (assoc k xs))) - -(defun al-has-value? (v xs) - "Return t if XS has a value of V." - (maybe-some? (rassoc v xs))) - -(defun al-count (xs) - "Return the number of entries in XS." - (length xs)) - -;; TODO: Should I support `al-find-key' and `al-find-value' variants? -(defun al-find (p xs) - "Find an element in XS. - -Apply a predicate fn, P, to each key and value in XS and return the key of the -first element that returns t." - (let ((result (list-find (lambda (x) (funcall p (car x) (cdr x))) xs))) - (if result - (car result) - nil))) - -(defun al-map-keys (f xs) - "Call F on the values in XS, returning a new alist." - (list-map (lambda (x) - `(,(funcall f (car x)) . ,(cdr x))) - xs)) - -(defun al-map-values (f xs) - "Call F on the values in XS, returning a new alist." - (list-map (lambda (x) - `(,(car x) . ,(funcall f (cdr x)))) - xs)) - -(defun al-reduce (acc f xs) - "Return a new alist by calling F on k v and ACC from XS. -F should return a tuple. See tuple.el for more information." - (->> (al-keys xs) - (list-reduce acc - (lambda (k acc) - (funcall f k (al-get k xs) acc))))) - -(defun al-merge (a b) - "Return a new alist with a merge of alists, A and B. -In this case, the last writer wins, which is B." - (al-reduce a #'al-set b)) - -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; -;; Tests -;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; - -(when al-enable-tests? - (prelude-assert - (equal '((2 . one) - (3 . two)) - (al-map-keys #'1+ - '((1 . one) - (2 . two))))) - (prelude-assert - (equal '((one . 2) - (two . 3)) - (al-map-values #'1+ - '((one . 1) - (two . 2)))))) - - -;; TODO: Support test cases for the entire API. - -(provide 'al) -;;; al.el ends here |