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Preface

Why Study Emacs Lisp?
On Reading this Text
For Whom This is Written
Lisp History
A Note for Novices
Thank You

List Processing

Lisp Lists
- Numbers, Lists inside of Lists
  Lisp Atoms
  Whitespace in Lists
  GNU Emacs Helps You Type Lists
Run a Program
Generate an Error Message
Symbol Names and Function Definitions
The Lisp Interpreter
- Complications
  Byte Compiling
Evaluation
- How the Lisp Interpreter Acts
  Evaluating Inner Lists
Variables
- fill-column, an Example Variable
  Error Message for a Symbol Without a Function
  Error Message for a Symbol Without a Value
Arguments
- Arguments’ Data Types
  An Argument as the Value of a Variable or List
  Variable Number of Arguments
  Using the Wrong Type Object as an Argument
  The message Function
Setting the Value of a Variable
- Using setq
  Counting
Summary
Exercises

Practicing Evaluation

How to Evaluate
Buffer Names
Getting Buffers
Switching Buffers
Buffer Size and the Location of Point
Exercise

How To Write Function Definitions

An Aside about Primitive Functions
The defun Macro
Install a Function Definition
- The effect of installation
  Change a Function Definition
Make a Function Interactive
- An Overview
  An Interactive multiply-by-seven
Different Options for interactive
Install Code Permanently
let
- let Prevents Confusion
  The Parts of a let Expression
  Sample let Expression
  Uninitialized Variables in a let Statement
  How let Binds Variables
  - Differences Between Lexical and Dynamic Binding
    Example of Lexical vs. Dynamic Binding
The if Special Form
- if in more detail
  The type-of-animal Function in Detail
If–then–else Expressions
Truth and Falsehood in Emacs Lisp
- An explanation of nil
save-excursion
- Point and Mark
  Template for a save-excursion Expression
Review
Exercises

A Few Buffer-Related Functions

Finding More Information
A Simplified beginning-of-buffer Definition
The Definition of mark-whole-buffer
- An overview of mark-whole-buffer
  Body of mark-whole-buffer
The Definition of append-to-buffer
- An Overview of append-to-buffer
  The append-to-buffer Interactive Expression
  The Body of append-to-buffer
  save-excursion in append-to-buffer
Review
Exercises

A Few More Complex Functions

The Definition of copy-to-buffer
The Definition of insert-buffer
- The Code for insert-buffer
  The Interactive Expression in insert-buffer
  - A Read-only Buffer
    ‘b’ in an Interactive Expression
  The Body of the insert-buffer Function
  insert-buffer With an if Instead of an or
  The or in the Body
  The let Expression in insert-buffer
  New Body for insert-buffer
Complete Definition of beginning-of-buffer
- Optional Arguments
  beginning-of-buffer with an Argument
  - Disentangle beginning-of-buffer
    What happens in a large buffer
    What happens in a small buffer
  The Complete beginning-of-buffer
Review
optional Argument Exercise

Narrowing and Widening

The Advantages of Narrowing
The save-restriction Special Form
what-line
Exercise with Narrowing

car, cdr, cons: Fundamental Functions

Strange Names
car and cdr
cons
- Build a list
  Find the Length of a List: length
nthcdr
nth
setcar
setcdr
Exercise

Cutting and Storing Text

Storing Text in a List
zap-to-char
- The Complete zap-to-char Implementation
  The interactive Expression
  The Body of zap-to-char
  The search-forward Function
  The progn Special Form
  Summing up zap-to-char
kill-region
- The Complete kill-region Definition
  condition-case
  Lisp macro
copy-region-as-kill
- The complete copy-region-as-kill function definition
  The Body of copy-region-as-kill
  - last-command and this-command
    The kill-append function
    The kill-new function
Digression into C
Initializing a Variable with defvar
- Seeing the Current Value of a Variable
  defvar and an asterisk
Review
Searching Exercises

How Lists are Implemented

Lists diagrammed
Symbols as a Chest of Drawers
Exercise

Yanking Text Back

Kill Ring Overview
The kill-ring-yank-pointer Variable
Exercises with yank and nthcdr

Loops and Recursion

while
- Looping with while
  A while Loop and a List
  An Example: print-elements-of-list
  A Loop with an Incrementing Counter
  Details of an Incrementing Loop
  - Example with incrementing counter
    the function definition
    Putting the function definition together
  Loop with a Decrementing Counter
  - Example with decrementing counter
    the function definition
    Putting the function definition together
Save your time: dolist and dotimes
- The dolist Macro
  The dotimes Macro
Recursion
- Building Robots: Extending the Metaphor
  The Parts of a Recursive Definition
  Recursion with a List
  Recursion in Place of a Counter
  - An argument of 1 or 2
    An argument of 3 or 4
  Recursion Example Using cond
  Recursive Patterns
  - Recursive Pattern: every
    Recursive Pattern: accumulate
    Recursive Pattern: keep
  Recursion without Deferments
  No Deferment Solution
Looping Exercise

Regular Expression Searches

The Regular Expression for sentence-end
The re-search-forward Function
forward-sentence
- Complete forward-sentence function definition
  The while loops
  The regular expression search
forward-paragraph: a Goldmine of Functions
- Shortened forward-paragraph function definition
  The let* expression
  The forward motion while loop
Review
Exercises with re-search-forward

Counting via Repetition and Regexps

Counting words
The count-words-example Function
- Designing count-words-example
  The Whitespace Bug in count-words-example
Count Words Recursively
Exercise: Counting Punctuation

Counting Words in a defun

Divide and Conquer
What to Count?
What Constitutes a Word or Symbol?
The count-words-in-defun Function
Count Several defuns Within a File
Find a File
lengths-list-file in Detail
Count Words in defuns in Different Files
- Determine the lengths of defuns
  The append Function
Recursively Count Words in Different Files
Prepare the Data for Display in a Graph
- The Data for Display in Detail
  Sorting Lists
  Making a List of Files
  Counting function definitions

Readying a Graph

Printing the Columns of a Graph
The graph-body-print Function
The recursive-graph-body-print Function
Need for Printed Axes
Exercise

Your .emacs File

Emacs’s Default Configuration
Site-wide Initialization Files
Specifying Variables using defcustom
Beginning a .emacs File
Text and Auto Fill Mode
Mail Aliases
Indent Tabs Mode
Some Key Bindings
- Legacy Global Key Binding Commands
Keymaps
Loading Files
Autoloading
A Simple Extension: line-to-top-of-window
X11 Colors
Miscellaneous Settings for a .emacs File
A Modified Mode Line

Debugging

debug
debug-on-entry
debug-on-quit and (debug)
The edebug Source Level Debugger
Debugging Exercises

Conclusion

The the-the Function

Handling the Kill Ring

What the Kill Ring Does
The current-kill Function
- The code for current-kill
  current-kill in Outline
  - The Body of current-kill
    Digression about the word “error”
    Determining the Element
yank
yank-pop
The ring.el File

A Graph with Labeled Axes

Labeled Example Graph
The print-graph Varlist
The print-Y-axis Function
- The print-Y-axis Function in Detail
  What height should the label be?
  Side Trip: Compute a Remainder
  Construct a Y Axis Element
  Create a Y Axis Column
  The Not Quite Final Version of print-Y-axis
The print-X-axis Function
- Similarities and differences
  X Axis Tic Marks
Printing the Whole Graph
- Changes for the Final Version
  Testing print-graph
  Graphing Numbers of Words and Symbols
  A lambda Expression: Useful Anonymity
  The mapcar Function
  Another Bug … Most Insidious
  The Printed Graph

Free Software and Free Manuals

GNU Free Documentation License

Index

About the Author

On this page

Exercise

Write a line graph version of the graph printing functions.

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How let Binds Variables

The Interactive Expression in insert-buffer

beginning-of-buffer with an Argument

The Body of copy-region-as-kill

Details of an Incrementing Loop

Loop with a Decrementing Counter

Recursion in Place of a Counter

Recursive Patterns

current-kill in Outline

Exercise ​

Exercise