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authorWilliam Carroll <wpcarro@gmail.com>2022-07-29T03·29-0700
committerclbot <clbot@tvl.fyi>2022-07-29T03·35+0000
commit15c9ff49026f9ddbb42f663dfbc2668faa74cab2 (patch)
tree23da6e794623f267bfcc53802cd654e3d655dba9 /users/wpcarro/emacs/pkgs/struct/struct.el
parentcaf068253a8e7eacff0b255de66f830e726d6777 (diff)
feat(wpcarro/emacs): Package al, list, set, struct r/4342
Originally I set-out to package `al.el`, but as I started traversing the
dependencies, I needed to package increasingly more packages. I refactored some
of these to prune their dependencies to slay this hydra before it turned into a
never-ending project. I have mixed feelings about this.

I also introduced `ert` and unit tests into my Elisp packaging, so it'll be nice
to have build-time tests that run when Emacs updates land in depot.

Change-Id: I2756dc60888b80255a495e08ae61bd547e6b3db2
Reviewed-on: https://cl.tvl.fyi/c/depot/+/5998
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI
Diffstat (limited to 'users/wpcarro/emacs/pkgs/struct/struct.el')
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+;;; struct.el --- Helpers for working with structs -*- lexical-binding: t -*-
+
+;; Author: William Carroll <wpcarro@gmail.com>
+;; Version: 0.0.1
+;; Package-Requires: ((emacs "24.3"))
+
+;;; Commentary:
+;; Provides new macros for working with structs.  Also provides adapter
+;; interfaces to existing struct macros, that should have more intuitive
+;; interfaces.
+;;
+;; Sometimes `setf' just isn't enough.
+
+;;; Code:
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Dependencies
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(require 's)
+(require 'dash)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Library
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defmacro struct-update (type field f xs)
+  "Apply F to FIELD in XS, which is a struct of TYPE.
+This is immutable."
+  (let ((copier (->> type
+                     symbol-name
+                     (s-prepend "copy-")
+                     intern))
+        (accessor (->> field
+                       symbol-name
+                       (s-prepend (s-concat (symbol-name type) "-"))
+                       intern)))
+    `(let ((copy (,copier ,xs)))
+       (setf (,accessor copy) (funcall ,f (,accessor copy)))
+       copy)))
+
+(defmacro struct-set (type field x xs)
+  "Immutably set FIELD in XS (struct TYPE) to X."
+  (let ((copier (->> type
+                     symbol-name
+                     (s-prepend "copy-")
+                     intern))
+        (accessor (->> field
+                       symbol-name
+                       (s-prepend (s-concat (symbol-name type) "-"))
+                       intern)))
+    `(let ((copy (,copier ,xs)))
+       (setf (,accessor copy) ,x)
+       copy)))
+
+(defmacro struct-set! (type field x xs)
+  "Set FIELD in XS (struct TYPE) to X mutably.
+This is an adapter interface to `setf'."
+  (let ((accessor (->> field
+                       symbol-name
+                       (s-prepend (s-concat (symbol-name type) "-"))
+                       intern)))
+    `(progn
+       (setf (,accessor ,xs) ,x)
+       ,xs)))
+
+(provide 'struct)
+;;; struct.el ends here