feat(wpcarro/emacs): Package fs.el

According to SourceGraph, this is unused, but I'm checking it in for historical
purposes.

Change-Id: I24bcb1c71a9f6de527bb54057cf13d01493c45bf
Reviewed-on: https://cl.tvl.fyi/c/depot/+/6016
Tested-by: BuildkiteCI
Reviewed-by: wpcarro <wpcarro@gmail.com>
Autosubmit: wpcarro <wpcarro@gmail.com>

users/wpcarro/emacs/pkgs/fs/fs.el

@@ -0,0 +1,47 @@
+;;; fs.el --- Make working with the filesystem easier -*- lexical-binding: t -*-
+
+;; Author: William Carroll <wpcarro@gmail.com>
+;; Version: 0.0.1
+;; Package-Requires: ((emacs "24.1"))
+
+;;; Commentary:
+;; Ergonomic alternatives for working with the filesystem.
+
+;;; Code:
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Dependencies
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(require 'dash)
+(require 'f)
+(require 's)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Library
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defun fs-ensure-file (path)
+  "Ensure that a file and its directories in `PATH' exist.
+Will error for inputs with a trailing slash."
+  (when (s-ends-with? "/" path)
+    (error (format "Input path has trailing slash: %s" path)))
+  (->> path
+       f-dirname
+       fs-ensure-dir)
+  (f-touch path))
+
+(defun fs-ensure-dir (path)
+  "Ensure that a directory and its ancestor directories in `PATH' exist."
+  (->> path
+       f-split
+       (apply #'f-mkdir)))
+
+(defun fs-ls (dir &optional full-path?)
+  "List the files in `DIR' one-level deep.
+Should behave similarly in spirit to the Unix command, ls.
+If `FULL-PATH?' is set, return the full-path of the files."
+  (-drop 2 (directory-files dir full-path?)))
+
+(provide 'fs)
+;;; fs.el ends here