BASIC (Beginners' All-purpose Symbolic Instruction Code) is a general-purpose high-level language from the 1960s. PuffinBASIC is an implementation of the BASIC language specification. PuffinBASIC conforms most closely to GWBASIC.
The purpose of this implementation is to learn how to write interpreters and resurrect an old programming language to work in modern ecosystem.
The interpreter is evolving fast and in near future, I wish to apply modern interpreter building techniques to it.
How it works?
1. PuffinBASIC's grammar is defined using antlr4.
2. At runtime, the user source code is parsed using antlr4 lexer+parser.
3. After parsing, an intermediate representation (IR) of the source code is generated. A symbol table keeps track of variables, scalars, arrays, etc. objects.
4. A runtime, processes the IR instructions and executes them.
PuffinBASIC is an interpreter, and it should not be expected to have very good performance characteristics. Certain operations such as PRINT USING, INPUT, etc. are not optimized for performance. I have not benchmarked PuffinBASIC primitives. That being said, we have written games with graphics in PuffinBASIC is work very well.
TESSEL - A 2D Tile Game written in PuffinBASIC
Link to YouTube video demo: https://youtu.be/L8xkM-g3Zms
PuffinBASIC runs within a JVM and can use as much memory as available for the JVM process.
PuffinBASIC is mostly compatible with Microsoft's GWBASIC. Graphics is supported using Java 2D graphics. PuffinBASIC will not support assembly instructions.
PuffinBASIC has extended BASIC types and supports Int32, Int4, Float32, Float64, and String.