Back when I were a lad, if you bought a computer, you'd bring it home and plug it into the telly and turn it on and a BASIC prompt would appear.

Tough luck if you wanted to do practical tasks like word processing, but you could type a single command (such as CIRCLE 100,100,50 ) and be instantly treated to a circle appearing on the screen. Before long, my generation were writing programs to crunch numbers for our statistics homework, and lots and lots of games. And thus a generation of software engineers was born.

Getting started in programming is trickier for the contemporary twenty-first-century child; they have to install a software development environment (their computer probably didn't come with one), and then go through a wizard to Create New Project, write initialisation code to open a window, then write a redraw event handler that takes a graphics context and draws a circle with it. A little less approachable than " CIRCLE 100,100,50 ". At least you get a simple word processor and a Web browser out of the box, though... I'm no nostalgic Luddite 🙂

Now, the Raspberry Pi has been widely hailed as the answer to our woes; costing just twenty pounds and usable given access to a TV and a dirt cheap USB keyboard and SD card, it's cheap enough to be purchased and given to a child to play with, unlike Mummy's laptop. Also, it has a user I/O port, meaning it should be relatively easily to integrate with home-built robots and other such fun electronics projects.

However, that's just the hardware side. What's seriously lacking is the software. If you buy a Pi and install one of the available Linux images onto an SD card and boot it up, you'll be presented with a Linux desktop environment. You'll be able to get to a shell prompt with little effort, and start learning shell, or get into a Python prompt and start to write Hello World, but that's not incredibly inviting; the effort required to do anything interesting from there is quite high. In particular, getting graphics going is hardly a job for a beginner.

So, I set out to improve on this situation. I've written a turtle graphics engine on top of Chicken Scheme, called Simple Graphics. Installing it is often painful as you need to get all the required bits of SDL and Cairo installed, but once that's done, thanks to Chicken's excellent egg system, installing simple-graphics is easy. And once you've done so, it's just a matter of:

(use simple-graphics) (forward 10)

...to get started with drawing things on the screen.

However, that initial installation pain can be bypassed by making a Raspberry Pi image, based on the existing excellent work on basic Linux distributions for the Pi, that has Chicken and simple-graphics pre-installed, with a desktop icon to fire up a Chicken prompt with the simple-graphics library already loaded so you don't need the use line. But then I'd also like to add Chicken eggs to drive the I/O port on the Pi, including I2C and SPI. And sound generation, so you can make noises to go with your graphics while driving a real robot turtle through the I/O port...

It would also be good to have a version that boots straight into a full-screen Chicken prompt (which, if you start doing turtle graphics commands, splits into two, a graphics area that can be hidden/revealed/made full screen with hot keys, and the command-line area), for people using small screens.

That way, kids of all ages could immediately have an interactive environment that lets them program the full range of capabilities of the Pi. And being based on Scheme, it wouldn't be a "dumbed down" environment they'll grow out of and have to learn a new language in order to do more powerful things; they'll be able to use all the Chicken Eggs available, as well as being able to write their own code in a language eminently capable of the full range of programming tasks - yet still simple enough for anybody to get started with. Sure, I could have based Simple Graphics on Python or Ruby; but anything they can do, Scheme can do better.