I just put the finishing touches on a tiny little interpreter project: Jasic. Jasic is a dialect of the original BASIC programming language. It lacks functions and scope, but it’s a usable language. Even on an old Apple IIe, it was powerful enough to get me hooked on coding for life. Also, you can draw a Mandelbrot set with it.

I wanted to see if I could fit a complete interpreter in a single readable Java file. It worked out better than expected, so I went ahead and cleaned up the code and commented the hell out of it. If you’ve always wanted to learn more about interpreters, now you’ve got a little primer.

Here’s a little code to give you a flavor of the language:

' initialize the loop counter
count = 10

' stop looping if we're done
top:
if count = 0 then end
print "Hello, world!"

' decrement and restart the loop
count = count - 1
goto top
end:

Old school! All of the code is right here in Jasic.java. There’s also a README to help get you started. What are you waiting for?

Discuss this at one of the sites below (or another of your choice):

If you want to contact me directly, feel free to email at "name@site" where "name" is "robert" and "site" is "stuffwithstuff.com".

© 2008-2009 Robert Nystrom