fix to setting custom variable and update README

README.md

@@ -1,6 +1,62 @@
-# lisp-diary: a note taking diary with Lisp in major mode
+# lisp-diary: A simple flat file-formatted diary app.
+
+The goal of `lisp-diary` is to simplify writing diary entries so that you spend less time learning the tool, and more time writing your personal notes, reminders or bits of information that have no home. One file for all your diary entries, with a simple format. `lisp-diary` is not meant to produce nicely formatted or styled notes. Other specialized tools are more appropriate for these.
+
+Basically, `lisp-diary` allows you to write diary notes in a Lisp file, which the app manages through a simple set of commands. 
+
+A Lisp file is a file that contains code with valid Lisp syntax. The app defaults to the [Emacs Lisp](https://en.wikipedia.org/wiki/Emacs_Lisp) dialect.
+
+> See [An Introduction to Programming in Emacs Lisp](https://www.gnu.org/software/emacs/manual/html_node/eintr/index.html) for a beginner's introduction to Elisp.
+
+A typical diary entry consists of three sections, in the following order:
+
+  * a date
+  * a note inside double quotation marks `"..."`
+    * a note can be anything like a reminder to do something.
+    * placing the note in these quotation marks allows the note to be distinguishabled visually from the date line and other Lisp expressions.
+  * Lisp expressions
+
+## Why use this format?
+
+By using a Lisp file for your diary notes in Emacs, you can:
+
+  * define reference mathematical formulas, that can be run within the buffer.
+  * do quick calculations without reaching out to a different window (or minibuffer).
+  * leverage other existing functions defined in Emacs.
+  * get Lisp editing facilities (Emacs Lisp major mode):
+    * code indentation
+    * parameter hints as expressions are typed
+    * code completion (C-M-i)
+
+> See [Evaluating Emacs Lisp Expressions](https://www.gnu.org/software/emacs/manual/html_node/emacs/Lisp-Eval.html) for more info.
+
+### Example ###
+
+Let's assume you are planning to bake chocolate eclairs. You write down the recipe, which calls for 140 grams of flour. However, you need to make 4 times as much and you want the weight to be in ounces.
+
+> You can write down the Lisp code and evalute it right there to get the result without leaving your notes.
+
+You might also find out that you need to convert grams to ounces frequently.
+
+> You can define a function to reuse in difference places in the future.
+
+
+```elisp
+
+;; Sat May 20 2023
+
+"Chocolate eclairs: 140g flour, 125ml milk, 4 eggs"
+
+(* 4 (* 140 0.035274)) ; 19.75344
+
+(defun grams-to-oz (g) (* g 0.035274))
+
+(grams-to-oz 140)
+
+```
+
+## Format of the diary file
 
-lisp-diary.el provides a simple format for a flat file to write diary entries along LISP forms.
 
 ```elisp
 ;;; notes.el --- notes w/ elisp -*- mode:emacs-lisp; -*-
@@ -18,18 +74,28 @@ lisp-diary.el provides a simple format for a flat file to write diary entries al
 ;; Thu May 18 2023
 "TODO:
 * ..."
+(+ 1 1)
 
 ;;; notes.el ends here
 ```
 
-The file can be located anywhere, and with version control.
+# Tagging notes
+
+You can tag notes by writing a list of topics inside brackets. This make searching through the notes easier, using the *topic-search* command.
 
-Diary notes go in the `"..."` forms. Topics to refer to later on these notes can be indicated with the syntax `[topicA ...]`.
+For example, let's say you occasionally find nice articles to read. You can add a link to the article and tag it with `[article]` within your diary entry for the day.
+Later, you can review the list of articles simply by doing a *topic-search* with the word article. If you need to be more specific in your topic search, for example, looking only for coding related articles, then you can simply expand that in the tag `[article coding]`.
 
 # Basic workflow: #
 
-  * Initially, place the `lisp-diary.el` in your load path.
-  * M-x todays-notes and choose the desired location for the notes.
-  * M-x add-days will insert at cursor a number of new days to the diary.
-  * M-x topic-search and enter some keywords to search existing topics.
-    * with a prefix, search directly in the buffer, rather than using Occur.
+  * Place the `lisp-diary.el` in your load path.
+  * **M-x todays-notes**
+      * This command takes you to the your diary notes file _at today's date_.
+      * If your diary notes file is not set, it will prompt you to choose the desired location for the notes.
+  * **M-x add-days**
+    * Because the app doesn't automatically insert new blank diary entries into the file, use this command to add as many such entries as you need.
+  * **M-x topic-search**
+    * This command will search notes you have tagged. Enter space delimited words to search for. The word order does not matter.
+    * The more words you add, the more refined the search is. Note that you should already have the notes tagged with all these words.
+    * With a prefix **C-u M-x topic-search**, search directly in the buffer, rather than getting the search results in a separate buffer.
+      * use **C-x z** to repeat the topic-search command

lisp-diary.el

@@ -80,7 +80,7 @@ N must be a positive integer."
                      "Notes path unset. Choose notes path: "
                      (expand-file-name "~/notes/") nil
                                 nil "")))
-    (customize-set-variable 'lisp-diary-path notes-path)))
+    (customize-save-variable 'lisp-diary-path notes-path)))
 
 (defun todays-notes (filename)
   "Open notes in FILENAME and set location to today's date.