Add show notes from Learning Emacs Lisp Ep 1

README.org

@@ -25,6 +25,10 @@ Here is a list of all the episode videos with links to the configuration we buil
 9. [[https://youtu.be/wa_wZIuT9Vw][Learn to Love the Terminal Modes]] ([[https://github.com/daviwil/emacs-from-scratch/tree/bbfbc77b3afab0c14149e07d0ab08d275d4ba575][Code]])
 10. [[https://youtu.be/PMWwM8QJAtU][Effortless File Management with Dired]] ([[https://github.com/daviwil/emacs-from-scratch/blob/8c302a79bf5700f6ef0279a3daeeb4123ae8bd59/Emacs.org#dired][Code]])
 
+** [[https://www.youtube.com/watch?v=RQK_DaaX34Q&list=PLEoMzSkcN8oPQtn7FQEF3D7sroZbXuPZ7][Learning Emacs Lisp]]
+
+1. [[https://youtu.be/RQK_DaaX34Q][Introduction to Emacs Lisp]] (Notes)
+
 ** [[https://www.youtube.com/playlist?list=PLEoMzSkcN8oNPbEMYEtswOVTvq7CVddCS][Emacs Desktop Environment]]
 
 1. [[https://www.youtube.com/watch?v=f7xB2fFk1tQ][Getting Started with EXWM]] ([[https://github.com/daviwil/emacs-from-scratch/blob/219c060e1bd695948c7691955a12a5dcaf3a9530/Emacs.org#window-management][Code]], [[file:show-notes/Emacs-Desktop-01.org][Notes]])

show-notes/Emacs-Lisp-01.org

@@ -0,0 +1,249 @@
+#+title: Introduction to Emacs Lisp
+
+* What will we cover?
+
+This is meant to be a practical series!
+
+- Emacs Lisp fundamentals
+- Everything about functions and variables
+- Manipulating Emacs
+- Working with the system
+- Creating and using extensibility points
+- Writing macros
+- Publishing to MELPA
+
+We will work on at least one new package as an example!
+
+* Who is this series for?
+
+- Not only for programmers!
+- Everyone should get to enjoy hacking Emacs
+
+If you know Lisp well, don't worry if I skip concepts!
+
+* What is Lisp?
+
+- That weird language with Lots of Irritating Superfluous Parentheses
+- A language and environment based on the idea of interactivity
+- The syntax enables new language constructs to be defined
+- The ultimate hacker language!
+
+* Emacs Lisp
+
+- A dialect of Lisp for configuring and extending Emacs
+- Much of Emacs' built-in functionality is written with it!
+- Has core features geared toward discoverability and extensibility
+- APIs and data types for many types special to Emacs (buffers, windows, etc)
+
+We will focus on core concepts in this video!
+
+* Lisp Syntax
+
+The beauty of Lisp comes from the simplicity of its syntax!
+
+Lisp syntax is primarily composed of lists, symbols, and values.
+
+#+begin_src emacs-lisp
+  (defun the-meaning-of-life (answer)
+    (message "The answer is %s" answer))
+
+  ;; Newlines and whitespace can be added anywhere in lists
+  (list 1 2 3
+        4 5 6
+        7 8 9)
+#+end_src
+
+The code can also be treated as data!
+
+You shouldn't be afraid of editing code with parentheses, there are packages for that :)
+
+* Values (or "Objects")
+
+Any value, or object, has a type.  It also has a textual representation that may or may not be "readable"!
+
+** Lisp Types
+
+- Strings
+- Numbers (both integer and float)
+- Symbols
+- Cons cells
+- Arrays and Vectors
+- ... and more
+
+https://www.gnu.org/software/emacs/manual/html_node/elisp/Programming-Types.html#Programming-Types
+
+** Emacs Types
+
+There are many types specific to Emacs as well, most don't have a code representation:
+
+- Buffers
+- Windows
+- Frames
+- Threads
+- Keymaps
+- ...
+
+Things we do with these types can affect the Emacs interface:
+
+#+begin_src emacs-lisp
+
+  ;; Get the previous buffer and switch to it
+  (switch-to-buffer (other-buffer))
+
+#+end_src
+
+https://www.gnu.org/software/emacs/manual/html_node/elisp/Editing-Types.html#Editing-Types
+
+* Forms and Evaluation
+
+A "form" is any lisp object that can be evaluated.
+
+** How evaluation works
+
+Evaluation works differently for:
+
+- Lists
+- Symbols
+- All other object types
+
+Some are [[https://www.gnu.org/software/emacs/manual/html_node/elisp/Self_002dEvaluating-Forms.html#Self_002dEvaluating-Forms][self-evaluating]], meaning that they return their own value:
+
+#+begin_src emacs-lisp
+
+;; Primitives are usually self-evaluating
+42
+
+"Hello!"
+
+[1 2 (+ 1 2)]
+
+;; Not self-evaluating!
+buffer-file-name
+
+;; Evaluates a function!
+(+ 300 11)
+
+(300 100)
+
+;; Some representations can't be evaluated!
+#<buffer Emacs-Lisp-01.org>
+
+#+end_src
+
+** The "Environment"
+
+Everything is evaluated in terms of Emacs Lisp's global environment!
+
+Pros: you can change anything in the environment as you go
+Cons: your environment might get "dirty" over time in your Emacs session
+
+#+begin_src emacs-lisp
+
+  ;; Set the initial value
+  (setq efs/our-nice-variable "Hello System Crafters!")
+
+  ;; Change it to something else (even a different type!)
+  (setq efs/our-nice-variable 1337)
+
+#+end_src
+
+** Expressions
+
+Lisp is an expression-based language, almost all forms return a value.
+
+#+begin_src emacs-lisp
+
+  ;; A very useful function...
+  (defun add-42 (num)
+    (+ num 42))
+
+  ;; It returns the result
+  (add-42 58)
+
+  ;; Using the result in another call
+  (* (add-42 58) 100)
+
+#+end_src
+
+* Symbols
+
+A symbol is also a type of object, but it's not self-evaluating!
+
+Symbols can contain alphanumeric characters plus many others:
+
+#+begin_src sh
+
+  # Possible symbol characters
+  - + = * / _ ~ ! @ $ % ^ & : < > { } ?
+
+#+end_src
+
+This gives you the ability to ascribe meanings to symbols based on the characters they contain.  Some examples:
+
+- =bui-keyword->symbol= - Convert from one type to another
+- =efs/some-name= - Define a "namespace" for the symbol
+- =*pcache-repositories*= - Indicates a global variable (not common in Emacs Lisp)
+- =string== - Check if something is equal to something else
+
+When a symbol is evaluated, it returns the variable value associated with that binding:
+
+#+begin_src emacs-lisp
+
+  ;; The example we saw before
+  buffer-file-name
+
+#+end_src
+
+Function names can't be evaluated like this though:
+
+#+begin_src emacs-lisp
+
+  get-file-buffer
+
+#+end_src
+
+We will discuss this point more in a future episode.
+
+https://www.gnu.org/software/emacs/manual/html_node/elisp/Symbol-Type.html#Symbol-Type
+
+* Infix vs Prefix
+
+Lisp expressions use "prefix" notation:
+
+#+begin_src emacs-lisp
+
+(+ 300 (- 12 1))
+
+#+end_src
+
+Why is this useful?  Because it puts all functions and operators at the same level of importance, even the ones you define!
+
+* Exercise
+
+Open up the =*scratch*= buffer and experiment with writing simple expressions.  Use =C-x C-e= (=eval-last-sexp=) at the end of each expression to evaluate them.
+
+Here are some you can try:
+
+#+begin_src emacs-lisp
+
+  42
+
+  (* 42 10)
+
+  (concat "Hello " "Emacs!")
+
+  ;; Simple list
+  '(1 2 3)
+
+  ;; Another way to create a list
+  (list 1 2 3)
+
+  ;; Get the second
+  (car (car '(1 2 3)))
+
+  ;; A vector
+  [1 2 3]
+
+#+end_src
+
+Also, go take a look at your Emacs configuration and see what things you can recognize about it now!