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Starting E
and Elmer

*** This chapter is obsolete and needs to be rewritten. There is no more "elmer", and the "e" command has been replaced by the bash script "rune", which has no icon. When installing (currently, only on MSWindows), you get a different pair of icons: one for eBrowser and one for capDesk. Both of these need to be documented.

Once you've followed the instructions on the Download page, you should have E installed. Your start menu should now have an entry named, that has sub-entries for e and elmer. If you launch e, you should see a new MS-DOS-like shell window in which an E interpreter is prompting you with a question mark. When you type an E expression at the question mark, E will run the expression and show you the resulting value:

? 2 + 3
# value: 5          

? _

You can terminate your rune window by typing a Ctrl-Z. This is done by holding down the Control key (marked "Ctrl" on many keyboards) and typing a "z" the next time you are prompted for input.

This kind of direct interaction with the rune command is great for one line programs, but multi-line programs need to be edited before they are executed. elmer is a minimal gui environment for prototyping small E programs.

When you launch elmer, you should see a Notepad-like text editor window. This lets you edit plain-text with embedded code examples, such as a plain-text version of this chapter. In elmer, you engage the E interpreter by starting an embedded example. You start an example by typing a line whose first non-whitespace character is a question mark:

Untitled - Elmer
File Edit Search Help
For example, E does arithmetic

    ? 2 + 3
    # value: 5

    ? |
In the pre-elmer example, e typed "?", you typed "2 + 3", and e typed "# value: 5". In this example, you typed "? 2 + 3" and elmer typed "# value: 5" while also repeating your indentation. However, elmer then types the next question mark (also indented), making it as easy to enter a sequence of examples as it is with e. To go back to editing plain-text, just backspace over the question mark.

In addition, elmer lets you save, open, and edit these interpreter sessions just as Notepad lets you save, open, and edit plain-text files. Before conversion to html, many of the pages at the site were first written in elmer, and assume you will use elmer to try out their examples. Eventually, we expect to run all our documentation as a readable automated regression test.

You exit elmer as you would Notepad or any other window-based Windows program.

Unless stated otherwise, all text on this page which is either unattributed or by Mark S. Miller is hereby placed in the public domain.
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