### 1.3 The Interpreted Environment ¶

The Yorick program accepts only complete input lines typed at your keyboard. Typing a command to Yorick presumes a “command line interface” or a “terminal emulator” which is not a part of Yorick. I designed Yorick on the assumption that you have a good terminal emulator program. In particular, Yorick is much easier to use if you can recall and edit previous input lines; as in music, repitition with variations is at the heart of programming. My personal recommendation is the yorick command in GNU Emacs (defined in yorick.el).

Therefore, Yorick inherits most of its “look and feel” from your terminal emulator. Yorick’s distinctive prompts and error messages are described later in this section.

Any significant Yorick program will be stored in a text file, called an include file, after the command which reads it. Use your favorite text editor to create and modify your include files. Again, GNU Emacs is my favorite — use the yorick-mode (defined in yorick.el) to edit Yorick include files as well as C programs. Just as C source file names should end in `.c` or `.h`, and Fortran source file names should end in `.f`, so Yorick include file names should end in `.i`.

This section begins with additional stylistic suggestions concerning include files. In particular, Yorick’s `help` command can find documentation comments in your include files if you format them properly. All of the built-in Yorick functions, such as `sin`, `write`, or `plg`, come equipped with such comments.