feat(wpcarro/emacs): Package symbol.el r/4359

Not sure how useful this package is, *but* I'm packaging everything I have now,
and then in a separate CL I can refactor and remove various libs.

Change-Id: Id106539b19244ea1586198992c7ce0d65a0a242b
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6014
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>
Tested-by: BuildkiteCI

3 files changed, 84 insertions, 0 deletions

diff --git a/users/wpcarro/emacs/pkgs/symbol/default.nix b/users/wpcarro/emacs/pkgs/symbol/default.nix
new file mode 100644
index 000000000000..9334697e3203
--- /dev/null
+++ b/users/wpcarro/emacs/pkgs/symbol/default.nix
@@ -0,0 +1,24 @@
+{ pkgs, depot, ... }:
+
+let
+  symbol = pkgs.callPackage
+    ({ emacsPackages }:
+      emacsPackages.trivialBuild {
+        pname = "symbol";
+        version = "1.0.0";
+        src = ./symbol.el;
+        packageRequires = [ ];
+      })
+    { };
+
+  emacs = (pkgs.emacsPackagesFor pkgs.emacs28).emacsWithPackages (epkgs: [
+    symbol
+  ]);
+in
+symbol.overrideAttrs (_old: {
+  doCheck = true;
+  checkPhase = ''
+    ${emacs}/bin/emacs -batch \
+      -l ert -l ${./tests.el} -f ert-run-tests-batch-and-exit
+  '';
+})
diff --git a/users/wpcarro/emacs/pkgs/symbol/symbol.el b/users/wpcarro/emacs/pkgs/symbol/symbol.el
new file mode 100644
index 000000000000..4b16351831c9
--- /dev/null
+++ b/users/wpcarro/emacs/pkgs/symbol/symbol.el
@@ -0,0 +1,38 @@
+;;; symbol.el --- Library for working with symbols -*- lexical-binding: t -*-
+
+;; Author: William Carroll <wpcarro@gmail.com>
+;; Version: 0.0.1
+;; Package-Requires: ((emacs "24"))
+
+;;; Commentary:
+;; Library for working with symbols.
+
+;;; Code:
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Library
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defun symbol-to-string (symbol)
+  "Map `SYMBOL' into a string."
+  (symbol-name symbol))
+
+(defun symbol-from-string (string)
+  "Map `STRING' into a symbol."
+  (intern string))
+
+(defun symbol-as-string (f x)
+  "Treat the symbol, X, as a string while applying F to it.
+Coerce back to a symbol on the way out."
+  (symbol-from-string (funcall f (symbol-to-string x))))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Predicates
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defun symbol-instance? (x)
+  "Return t if X is a symbol."
+  (symbolp x))
+
+(provide 'symbol)
+;;; symbol.el ends here
diff --git a/users/wpcarro/emacs/pkgs/symbol/tests.el b/users/wpcarro/emacs/pkgs/symbol/tests.el
new file mode 100644
index 000000000000..b10362b162c7
--- /dev/null
+++ b/users/wpcarro/emacs/pkgs/symbol/tests.el
@@ -0,0 +1,22 @@
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Dependencies
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(require 'ert)
+(require 'symbol)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Tests
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(ert-deftest symbol-to-string ()
+  (should (string= "foo" (symbol-to-string 'foo))))
+
+(ert-deftest symbol-from-string ()
+  (should (eq 'foo (symbol-from-string "foo"))))
+
+(ert-deftest symbol-as-string ()
+  (should (eq 'foo-hook
+              (symbol-as-string
+               (lambda (x) (format "%s-hook" x))
+               'foo))))