Sole 128

A simple interpreter and REPL with elements of a compiler

This was my first attempt at trying to understand how compilers work. It was also an opportunity to play with language constructs that would be easy for beginners to learn. I wouldn't expect anyone to use this--it's strictly for learning and fun.

• Language looks like basic
• Synchronous
• Interpreted in JavaScript
• Includes parsing/tokenizing; interpreter reads syntax tree
• HTML/CSS user interface for REPL and running code files

Some supported language features include:

• string (a$), integer (a%), float (a) and array (a[]) types
• loops with step and to
• goto and gosub but without line numbers, just labels
• most everything is an expression and returns a value always stored in the built-in ! (bang) variable
• input and print for getting user input and printing to screen
• basic math with add, subtract, multiply, divide
• if and then
• run command to run a file

See interpreter.js for a full list of supported statements and expressions. (This files also includes the parser.)

Examples of the languages can be found in code.prg and code_backup.prg.

sole128.js drives the REPL.

editor.prg is an attempt at writing an editor in Sole128.

kernal.js is the code that drives the UI (rendered with HTML canvas element)

Running it

Uses the node package http-server with npm start to serve up the /src directory, but any static server will do.

IMPORTANT: Code uses some APIs no longer present in modern browsers, and most things will not work.

• Clone the repo
• npm install -g http-server
• npm start
• Go to http://localhost:8000/sole128.html
• Try run "code.prg"

Demo

https://rscottfree.github.io/sole128/src/sole128.html You can run the example program by typing run "code.prg" and hitting enter.

Acknowledgments

The series of posts starting with the link below inspired this project. If you know nothing about where to start with building a compiler, try this.

http://noeffclue.blogspot.ca/2014/05/compiler-part-1-introduction-to-writing.html

The general structure of this follows closely what I did for Sole64, a now-defunct Chrome App I created for learning programming.