First Things First

A Programming Language?

Sophie is first and foremost a language for expressing ideas about computations that might happen. That means you can write and reason about Sophie programs without any computer. Sophie is meant to be suitable for the blackboard or publication in a magazine. There are no special formatting requirements.

Initial Preparations

But if you’d like to put your computer up to the task of evaluating (executing, running) Sophie programs, you’ll need two things:

  • An interpreter.

  • A code editor.

You can get an interpreter easily enough from the official Sophie repository on GitHub. Follow the directions at Getting Started and then come back here.

As for a code editor, you have lots of choices. But for what we’re doing, you won’t need anything too sophisticated. If you’re on Windows, you can use notepad. If you’re running a Macintosh or Linux machine, try searching your application menu for “text editor”.

Your First Program in Sophie

Virtually every programming tutorial starts the same way:

begin:
	"Hello, World!";
	"All done here.";
end.

If you followed directions earlier, you already have a copy of this program at examples/hello_world.sg.

Now suppose you’re at a command-prompt and you’ve set the current-directory to wherever you extracted Sophie. If you then run:

sophie examples/hello_world.sg

you will see:

Hello, World!
All done here.

Let’s break this down:

  • Sophie programs are files.

  • The main program begins with the phrase begin:.

  • Next comes a sequence of steps. Sophie follows those steps, one after another:

    • Each step is an expression of some value.

    • Sophie computes the value of that expression, and then displays the result.

    • Here we’ve only seen one kind of expression (the humble string) but there are other kinds to handle all of computing.

    • If that expression should happen to be a drawing, then the display is graphical. Sophie supports something called “Turtle Graphics”. Deets later.

  • Finally, every Sophie program ends with the phrase end. with a period.

    • Why? Because it looks nice in print.

    • Ok, the end. is now optional in response to some random dude on the internet with an opinion.

  • At the moment, Sophie is implemented as a Python program.

    • So in general, you will invoke sophie followed by the pathname to your program.

    • Some day, this may change. If you’d like to help that along, let’s talk about something called self-hosting.