# Scheme

Egon Animator uses Scheme for commands. This means that the program can be easily extended with new functions. When Load is chosen from the File menu, for instance, the Lisp function (load-buffer) is called. It is thus possible to make File - Load do something completely different by writing a new load-buffer function, perhaps adding the ability to read other file formats.

### Functions available as commands

(backward-cell)
  Move point one cell to the left.
(forward-cell)
  Move point one position to the right.
(next-line)
  Move point one line down.
(previous-line)
  Move point one line up.
(beginning-of-line)
  Move point to column 1.
(end-of-line)
  Move point to the last used position in the current line.
(beginning-of-buffer)
  Move point to column 1, line 1.
(end-of-buffer)
  Move point to the last used position in the last used line.
(top-of-buffer)
  Move point to line 1 without changing the column.
(bottom-of-buffer)
  Move point to the last used line without changing the column.
(scroll-up)
  Move the window up one windowful.
(scroll-cell-up)
  Move the window up one line.
(scroll-down)
  Move the window down one windowful.
(scroll-cell-down)
  Move the window down one line.
(scroll-left)
  Move the window left one windowful.
(scroll-cell-left)
  Move the window left one column.
(scroll-right)
  Move the window right one windowful.
(scroll-cell-right)
  Move the window right one column.
(what-cursor-position)
  Prints information about the current position on the status bar.
(delete-cell)
  Delete the contents of the current position.
(insert-line)
  Insert an empty line, moving the rest of the document down.
(set-mark-command)
  Move mark to the current position.
(exchange-point-and-mark)
  Swap point and mark.
(kill-region)
  Should delete everything between point and mark for compatibility with Emacs, but currently does nothing. Block commands are available for that purpose.
(copy-block)
  Copy the block to the current position.
(delete-block)
  Deletes all the block.
(print-block)
  Dumps the block to a text file.
(set-block)
  Sets the block to be the area between mark and point.
(save-block-file)
  What does this do?
(new-egon)
  Loads a new Egon Animator window.
(load-buffer)
  Loads a Egon Animator document into a new buffer.
(save-buffer)
  Saves the current buffer as an Egon Animator document.
(save-buffer-as)
  Saves the current buffer using a new file name.
(print-version)
  Prints version information on the status bar.
(help-contents)
  Starts the Chimera program with egon.html as argument.
(help-search)
  Search for keyword. Currently not implemented.
(help-for-help)
  Starts the Chimera program with siaghelp.html as argument.
(recenter)
  Redraws the screen.
(execute-extended-command)
  Read and execute a Scheme command.
(keyboard-quit)
  Abort a multi-key command sequence.
(quit-egon)
  Exit from Egon Animator. If there are any unsaved changes, asks if they should be saved.
(no-op)
  Does nothing. Sometimes useful for debugging.

There are two ways to execute Scheme code:

1. Pressing ( and typing it in the input window
2. Loading it from a file using (load "filename")

A file can be loaded on startup by giving the option -iFilename on the command line. A useful file to load is siod.scm which adds common functions like caar, cadr and the like.

## Commands

### (new-buffer)

Opens a new empty Egon Animator window.

### (load-buffer)

Asks for a file name and opens the file with that name as a Pathetic Writer document.

### (save-buffer)

Saves the currently open document using the most recently used filename. If no name has been given to the document, the name "noname" is used.

### (save-buffer-as)

Asks for a filename and saves the currently open document using that filename.

### (preview)

Preview the contents of the current buffer.

### (print)

Prints the current buffer using the lpr command.

### (quit-program)

Quits from Egon Animator. If there are any changes that have not been saved, Egon Animator asks if they should be saved.

### (switch-to-buffer)

Change which buffer is displayed in the current window.

### (kill-buffer)

Delete the current buffer.

### (split-window-vertically)

Split the current buffer in two.

### (delete-window)

Remove the current window and give its space to its neighbors.

### (delete-other-windows)

Remove all windows except the current one.

### (other-window)

Make the next window current.

### (help-contents)

Displays the Egon Animator online documentation.

### (help-search)

This command does nothing.

### (help-copyright)

Displays the GNU public licence.

### (help-for-help)

Displays help for using the online help.

### (print-version)

Displays the current version string.