Chapter 1.15 --- Extra Credit

Command-Line Utilities

"The trouble with lessons from history is that we usually read them best after falling flat on our chins."

Underlying every modern operating system is some sort of command-line. You may never have seen it before you began your journey with Lisp, but it's always been there---the real interface to your computer, on top of which all others are built. Compared to what you can do from the command-line, graphical user interfaces (no matter how sleek and intuitive), are clunky and slow, and hold you back.

As a programmer, all you need is this command-line---and it's worth your time to make it your best friend. You may have even noticed how power-users seem to go out of their way to strip out the GUI from their workspace, retrofitting their OS into a souped-up 80s-style text-only terminal. This is no mere affectation---it's all about productivity.

So now we're going to begin our journey of creating distributable Lisp binaries by creating a useful utility application that you can run from the command-line yourself, without having to open up Lisp first. It will run like any other program on your computer---and, if you have access to Windows, OS X, and Linux, you can create binary distributions of your software and provide them to your users instead of a source code release.

Command-Line Interfaces may not seem like a big deal to you, at first glance. You enter a few words in the terminal, and you get your output. Where's the challenge in that, right?

I suppose it is a matter of opinion, but in my experience, crafting a useful, productive command-line interface to an application is a much greater challenge than designing a point-and-click or touch-based GUI. After all, when the only thing your users have to guide them is what's output by the --help flag, the terminal can be a scary, lonely place if you didn't put enough thought into the arguments and documentation for your application.

This chapter will contain exercises on:

• Manually parsing arguments from the command-line
• Introducing CLON: The Command-Line Options Nuker
• Loading Quicklisp in Lisp Scripts, but mention that it is considered 'bad practice'
• Defining Your Application's Synopsis
• Defining Your Application's Event Loop
• Dumping Binaries
• Distributing your Text-Adventure as a Binary
• Deploying your Web App as a Daemon

Exercise 1.15.1

Manually parsing arguments from the command-line

Exercise 1.15.2

Introducing CLON: The Command-Line Options Nuker

Exercise 1.15.3

CLON: Synopsis

Exercise 1.15.4

CLON: Event Loop

Exercise 1.15.5

Introducing Buildapp

Exercise 1.15.6

Rewrite Your Text-Adventure to Use CLON and Buildapp

Exercise 1.15.7

Rewrite Your Web App as a Daemon