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Programming in Emacs Lisp

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This master menu first lists each chapter and index; then it lists every node in every chapter.

Preface    What to look for.
1. List Processing    What is Lisp?
2. Practicing Evaluation    Running several programs.
3. How To Write Function Definitions    How to write function definitions.
4. A Few Buffer--Related Functions    Exploring a few buffer-related functions.
5. A Few More Complex Functions    A few, even more complex functions.
6. Narrowing and Widening    Restricting your and Emacs attention to a region.
7. car, cdr, cons: Fundamental Functions    Fundamental functions in Lisp.
8. Cutting and Storing Text    Removing text and saving it.
9. How Lists are Implemented    How lists are implemented in the computer.
10. Yanking Text Back    Pasting stored text.
11. Loops and Recursion    How to repeat a process.
12. Regular Expression Searches    Regular expression searches.
13. Counting: Repetition and Regexps    A review of repetition and regexps.
14. Counting Words in a defun    Counting words in a defun.
15. Readying a Graph    A prototype graph printing function.
16. Your `.emacs' File    How to write a `.emacs' file.
17. Debugging    How to run the Emacs Lisp debuggers.
18. Conclusion    Now you have the basics.
A. The the-the Function    An appendix: how to find reduplicated words.
B. Handling the Kill Ring    An appendix: how the kill ring works.
C. A Graph with Labelled Axes    How to create a graph with labelled axes.
D. Free Software and Free Manuals   
E. GNU Free Documentation License   
About the Author   

 -- The Detailed Node Listing ---


Why Study Emacs Lisp?    Why learn Emacs Lisp?
On Reading this Text    Read, gain familiarity, pick up habits....
For Whom This is Written    For whom this is written.
Lisp History   
A Note for Novices    You can read this as a novice.
Thank You   

List Processing

1.1 Lisp Lists    What are lists?
1.2 Run a Program    Any list in Lisp is a program ready to run.
1.3 Generate an Error Message    Generating an error message.
1.4 Symbol Names and Function Definitions    Names of symbols and function definitions.
1.5 The Lisp Interpreter    What the Lisp interpreter does.
1.6 Evaluation    Running a program.
1.7 Variables    Returning a value from a variable.
1.8 Arguments    Passing information to a function.
1.9 Setting the Value of a Variable    Setting the value of a variable.
1.10 Summary    The major points.
1.11 Exercises   

Lisp Lists

Numbers, Lists inside of Lists    List have numbers, other lists, in them.
1.1.1 Lisp Atoms    Elemental entities.
1.1.2 Whitespace in Lists    Formatting lists to be readable.
1.1.3 GNU Emacs Helps You Type Lists    How GNU Emacs helps you type lists.

The Lisp Interpreter

Complications    Variables, Special forms, Lists within.
1.5.1 Byte Compiling    Specially processing code for speed.


How the Lisp Interpreter Acts    Returns and Side Effects...
1.6.1 Evaluating Inner Lists    Lists within lists...


fill-column, an Example Variable   
1.7.1 Error Message for a Symbol Without a Function    The error message for a symbol without a function.
1.7.2 Error Message for a Symbol Without a Value    The error message for a symbol without a value.


1.8.1 Arguments' Data Types    Types of data passed to a function.
1.8.2 An Argument as the Value of a Variable or List    An argument can be the value of a variable or list.
1.8.3 Variable Number of Arguments    Some functions may take a variable number of arguments.
1.8.4 Using the Wrong Type Object as an Argument    Passing an argument of the wrong type to a function.
1.8.5 The message Function    A useful function for sending messages.

Setting the Value of a Variable

1.9.1 Using set    Setting values.
1.9.2 Using setq    Setting a quoted value.
1.9.3 Counting    Using setq to count.

Practicing Evaluation

How to Evaluate    Typing editing commands or C-x C-e causes evaluation.
2.1 Buffer Names    Buffers and files are different.
2.2 Getting Buffers    Getting a buffer itself, not merely its name.
2.3 Switching Buffers    How to change to another buffer.
2.4 Buffer Size and the Location of Point    Where point is located and the size of the buffer.
2.5 Exercise   

How To Write Function Definitions

An Aside about Primitive Functions   
3.1 The defun Special Form    The defun special form.
3.2 Install a Function Definition    Install a function definition.
3.3 Make a Function Interactive    Making a function interactive.
3.4 Different Options for interactive    Different options for interactive.
3.5 Install Code Permanently    Installing code permanently.
3.6 let    Creating and initializing local variables.
3.7 The if Special Form    What if?
3.8 If--then--else Expressions    If--then--else expressions.
3.9 Truth and Falsehood in Emacs Lisp    What Lisp considers false and true.
3.10 save-excursion    Keeping track of point, mark, and buffer.
3.11 Review   
3.12 Exercises   

Install a Function Definition

The effect of installation   
3.2.1 Change a Function Definition    How to change a function definition.

Make a Function Interactive

An Interactive multiply-by-seven, An Overview    An overview.
3.3.1 An Interactive multiply-by-seven    The interactive version.


let Prevents Confusion   
3.6.1 The Parts of a let Expression   
3.6.2 Sample let Expression   
3.6.3 Uninitialized Variables in a let Statement   

The if Special Form

if in more detail   
3.7.1 The type-of-animal Function in Detail    An example of an if expression.

Truth and Falsehood in Emacs Lisp

An explanation of nil    nil has two meanings.


Point and Mark    A review of various locations.
3.10.1 Template for a save-excursion Expression   

A Few Buffer--Related Functions

4.1 Finding More Information    How to find more information.
4.2 A Simplified beginning-of-buffer Definition    Shows goto-char,
                                point-min, and push-mark.
4.3 The Definition of mark-whole-buffer    Almost the same as beginning-of-buffer.
4.4 The Definition of append-to-buffer    Uses save-excursion and
4.5 Review   
4.6 Exercises   

The Definition of mark-whole-buffer

An overview of mark-whole-buffer   
4.3.1 Body of mark-whole-buffer    Only three lines of code.

The Definition of append-to-buffer

An Overview of append-to-buffer   
4.4.1 The append-to-buffer Interactive Expression    A two part interactive expression.
4.4.2 The Body of append-to-buffer    Incorporates a let expression.
4.4.3 save-excursion in append-to-buffer    How the save-excursion works.

A Few More Complex Functions

5.1 The Definition of copy-to-buffer    With set-buffer, get-buffer-create.
5.2 The Definition of insert-buffer    Read-only, and with or.
5.3 Complete Definition of beginning-of-buffer    Shows goto-char,
                                point-min, and push-mark.
5.4 Review   
5.5 optional Argument Exercise   

The Definition of insert-buffer

The Code for insert-buffer   
5.2.1 The Interactive Expression in insert-buffer    When you can read, but not write.
5.2.2 The Body of the insert-buffer Function    The body has an or and a let.
5.2.3 insert-buffer With an if Instead of an or    Using an if instead of an or.
5.2.4 The or in the Body    How the or expression works.
5.2.5 The let Expression in insert-buffer    Two save-excursion expressions.
5.2.6 New Body for insert-buffer   

The Interactive Expression in insert-buffer

A Read-only Buffer    When a buffer cannot be modified.
`b' in an Interactive Expression    An existing buffer or else its name.

Complete Definition of beginning-of-buffer

5.3.1 Optional Arguments   
5.3.2 beginning-of-buffer with an Argument    Example with optional argument.
5.3.3 The Complete beginning-of-buffer   

beginning-of-buffer with an Argument

Disentangle beginning-of-buffer   
What happens in a large buffer   
What happens in a small buffer   

Narrowing and Widening

The Advantages of Narrowing    The advantages of narrowing
6.1 The save-restriction Special Form    The save-restriction special form.
6.2 what-line    The number of the line that point is on.
6.3 Exercise with Narrowing   

carcdrcons: Fundamental Functions

Strange Names    An historical aside: why the strange names?
7.1 car and cdr    Functions for extracting part of a list.
7.2 cons    Constructing a list.
7.3 nthcdr    Calling cdr repeatedly.
7.4 nth   
7.5 setcar    Changing the first element of a list.
7.6 setcdr    Changing the rest of a list.
7.7 Exercise   


Build a list   
7.2.1 Find the Length of a List: length    How to find the length of a list.

Cutting and Storing Text

Storing Text in a List    Text is stored in a list.
8.1 zap-to-char    Cutting out text up to a character.
8.2 kill-region    Cutting text out of a region.
8.3 copy-region-as-kill    A definition for copying text.
8.4 Digression into C    Minor note on C programming language macros.
8.5 Initializing a Variable with defvar    How to give a variable an initial value.
8.6 Review   
8.7 Searching Exercises   


The Complete zap-to-char Implementation    The complete implementation.
8.1.1 The interactive Expression    A three part interactive expression.
8.1.2 The Body of zap-to-char    A short overview.
8.1.3 The search-forward Function    How to search for a string.
8.1.4 The progn Special Form    The progn special form.
8.1.5 Summing up zap-to-char    Using point and search-forward.


The Complete kill-region Definition    The function definition.
8.2.1 condition-case    Dealing with a problem.
8.2.2 Lisp macro   


The complete copy-region-as-kill function definition    The complete function definition.
8.3.1 The Body of copy-region-as-kill    The body of copy-region-as-kill.

The Body of copy-region-as-kill

last-command and this-command   
The kill-append function   
The kill-new function   

Initializing a Variable with defvar

Seeing the Current Value of a Variable   
8.5.1 defvar and an asterisk   

How Lists are Implemented

Lists diagrammed   
9.1 Symbols as a Chest of Drawers    Exploring a powerful metaphor.
9.2 Exercise   

Yanking Text Back

10.1 Kill Ring Overview   
10.2 The kill-ring-yank-pointer Variable    The kill ring is a list.
10.3 Exercises with yank and nthcdr    The kill-ring-yank-pointer variable.

Loops and Recursion

11.1 while    Causing a stretch of code to repeat.
11.2 Save your time: dolist and dotimes   
11.3 Recursion    Causing a function to call itself.
11.4 Looping Exercise   


Looping with while    Repeat so long as test returns true.
11.1.1 A while Loop and a List    A while loop that uses a list.
11.1.2 An Example: print-elements-of-list    Uses while, car, cdr.
11.1.3 A Loop with an Incrementing Counter    A loop with an incrementing counter.
Details of an Incrementing Loop   
11.1.4 Loop with a Decrementing Counter    A loop with a decrementing counter.

Details of an Incrementing Loop

Example with incrementing counter    Counting pebbles in a triangle.
The parts of the function definition   
Putting the function definition together   

Loop with a Decrementing Counter

Example with decrementing counter    More pebbles on the beach.
The parts of the function definition   
Putting the function definition together   

Save your time: dolist and dotimes

The dolist Macro   
The dotimes Macro   


11.3.1 Building Robots: Extending the Metaphor    Same model, different serial number ...
11.3.2 The Parts of a Recursive Definition    Walk until you stop ...
11.3.3 Recursion with a List    Using a list as the test whether to recurse.
11.3.4 Recursion in Place of a Counter   
11.3.5 Recursion Example Using cond   
11.3.6 Recursive Patterns    Often used templates.
11.3.7 Recursion without Deferments    Don't store up work ...
11.3.8 No Deferment Solution   

Recursion in Place of a Counter

An argument of 1 or 2   
An argument of 3 or 4   

Recursive Patterns

Recursive Pattern: every   
Recursive Pattern: accumulate   
Recursive Pattern: keep   

Regular Expression Searches

12.1 The Regular Expression for sentence-end    The regular expression for sentence-end.
12.2 The re-search-forward Function    Very similar to search-forward.
12.3 forward-sentence    A straightforward example of regexp search.
12.4 forward-paragraph: a Goldmine of Functions    A somewhat complex example.
12.5 Create Your Own `TAGS' File    How to create your own `TAGS' table.
12.6 Review   
12.7 Exercises with re-search-forward   


Complete forward-sentence function definition   
The while loops    Two while loops.
The regular expression search    A regular expression search.

forward-paragraph: a Goldmine of Functions

Shortened forward-paragraph function definition    Key parts of the function definition.
The let* expression   
The forward motion while loop   

Counting: Repetition and Regexps

Counting words   
13.1 The count-words-region Function    Use a regexp, but find a problem.
13.2 Count Words Recursively    Start with case of no words in region.
13.3 Exercise: Counting Punctuation   

The count-words-region Function

Designing count-words-region    The definition using a while loop.
13.1.1 The Whitespace Bug in count-words-region   

Counting Words in a defun

Divide and Conquer   
14.1 What to Count?    What to count?
14.2 What Constitutes a Word or Symbol?    What constitutes a word or symbol?
14.3 The count-words-in-defun Function    Very like count-words.
14.4 Count Several defuns Within a File    Counting several defuns in a file.
14.5 Find a File    Do you want to look at a file?
14.6 lengths-list-file in Detail    A list of the lengths of many definitions.
14.7 Count Words in defuns in Different Files    Counting in definitions in different files.
14.8 Recursively Count Words in Different Files    Recursively counting in different files.
14.9 Prepare the Data for Display in a Graph    Prepare the data for display in a graph.

Count Words in defuns in Different Files

Determine the lengths of defuns    Return a list of the lengths of defuns.
14.7.1 The append Function    Attach one list to another.

Prepare the Data for Display in a Graph

The Data for Display in Detail   
14.9.1 Sorting Lists    Sorting lists.
14.9.2 Making a List of Files    Making a list of files.
14.9.3 Counting function definitions   

Readying a Graph

Printing the Columns of a Graph   
15.1 The graph-body-print Function    How to print the body of a graph.
15.2 The recursive-graph-body-print Function   
15.3 Need for Printed Axes   
15.4 Exercise   

Your `.emacs' File

Emacs' Default Configuration   
16.1 Site-wide Initialization Files    You can write site-wide init files.
16.2 Specifying Variables using defcustom    Emacs will write code for you.
16.3 Beginning a `.emacs' File    How to write a .emacs file.
16.4 Text and Auto Fill Mode    Automatically wrap lines.
16.5 Mail Aliases    Use abbreviations for email addresses.
16.6 Indent Tabs Mode    Don't use tabs with TeX
16.7 Some Keybindings    Create some personal keybindings.
16.8 Keymaps    More about key binding.
16.9 Loading Files    Load (i.e., evaluate) files automatically.
16.10 Autoloading    Make functions available.
16.11 A Simple Extension: line-to-top-of-window    Define a function; bind it to a key.
16.12 X11 Colors    Colors in X.
16.13 Miscellaneous Settings for a `.emacs' File   
16.14 A Modified Mode Line    How to customize your mode line.


17.1 debug    How to use the built-in debugger.
17.2 debug-on-entry    Start debugging when you call a function.
17.3 debug-on-quit and (debug)    Start debugging when you quit with C-g.
17.4 The edebug Source Level Debugger    How to use Edebug, a source level debugger.
17.5 Debugging Exercises   

Handling the Kill Ring

What the Kill Ring Does   
B.1 The current-kill Function   
B.2 yank    Paste a copy of a clipped element.
B.3 yank-pop    Insert element pointed to.
B.4 The `ring.el' File   

The current-kill Function

current-kill in Outline   

current-kill in Outline

The Body of current-kill   
Digression about the word `error'    How to mislead humans, but not computers.
Determining the Element   

A Graph with Labelled Axes

Labelled Example Graph   
C.1 The print-graph Varlist    let expression in print-graph.
C.2 The print-Y-axis Function    Print a label for the vertical axis.
C.3 The print-X-axis Function    Print a horizontal label.
C.4 Printing the Whole Graph    The function to print a complete graph.

The print-Y-axis Function

The print-Y-axis Function in Detail   
What height should the label be?    What height for the Y axis?
C.2.1 Side Trip: Compute a Remainder    How to compute the remainder of a division.
C.2.2 Construct a Y Axis Element    Construct a line for the Y axis.
C.2.3 Create a Y Axis Column    Generate a list of Y axis labels.
C.2.4 The Not Quite Final Version of print-Y-axis    A not quite final version.

The print-X-axis Function

Similarities and differences    Much like print-Y-axis, but not exactly.
C.3.1 X Axis Tic Marks    Create tic marks for the horizontal axis.

Printing the Whole Graph

Changes for the Final Version    A few changes.
C.4.1 Testing print-graph    Run a short test.
C.4.2 Graphing Numbers of Words and Symbols    Executing the final code.
C.4.3 A lambda Expression: Useful Anonymity    How to write an anonymous function.
C.4.4 The mapcar Function    Apply a function to elements of a list.
C.4.5 Another Bug ... Most Insidious    Yet another bug ... most insidious.
C.4.6 The Printed Graph    The graph itself!