The EndBASIC programming language - core

EndBASIC is an interpreter for a BASIC-like language and is inspired by Amstrad's Locomotive BASIC 1.1 and Microsoft's QuickBASIC 4.5. Like the former, EndBASIC intends to provide an interactive environment that seamlessly merges coding with immediate visual feedback. Like the latter, EndBASIC offers higher-level programming constructs and strong typing. The main idea behind EndBASIC is to provide a playground for learning the foundations of programming in a simplified environment.

EndBASIC is written in Rust. The parser and interpreter's primary goal is to be readable and easy to modify. A secondary goal is to make the core minimal, extensible, and configurable. Performance is not a goal right now, though it likely won't disappoint.

EndBASIC is free software under the Apache 2.0 License.

What's in this crate?

endbasic-core provides the language parser and interpreter, as well as the standard library. Note that exposing the standard library via the interpreter is optional, and this can be done on a command-by-command basis.

Language features

EndBASIC's language features are inspired by other BASIC interpreters but the language does not intend to be fully compatible with them. The language currently supports:

• Variable types: boolean (?), double (#), integer (%), and string ($).
• Strong typing with optional variable type annotations.
• IF ... THEN / ELSEIF ... THEN / ELSE / END IF statements.
• FOR x = ... TO ... [STEP ...] / NEXT loops.
• WHILE ... / END WHILE loops.
• UTF-8 everywhere (I think).
• Commands:
  • Console: CLS, COLOR, INPUT, LOCATE, PRINT.
  • Interpreter: CLEAR, EXIT, HELP.
  • Numerics: RANDOMIZE.
  • Program: DEL, DIR, EDIT, LOAD, NEW, RUN, SAVE.
• Functions:
  • Numerics: DTOI, ITOD, RND.
  • Strings: LEFT, LEN, LTRIM, MID, RIGHT, RTRIM.

Implementation features

Some highlights about the EndBASIC implementation are:

• Minimalist core. The interpreter knows how to execute the logic of the language but, by default, it exposes no builtins to the scripts—not even INPUT or PRINT. This makes EndBASIC ideal for embedding into other programs, as it is possible to execute external code without side-effects or by precisely controlling how such code interacts with the host program.

• Minimalist library. The standard library provides the logic for all built-in commands, but each command can be individually installed into the parser, and all interactions with the environment (e.g. the console, or the file system) are exposed via hooks that the caller needs to implement.

• Async support. The interpreter is async-compatible, making it trivial to embed it into Javascript via WASM.

Examples

You can peek into the tests subdirectory of this repository to see actual EndBASIC code samples. Look for all files with a .bas extension.

The examples directory contains sample code to show how to embed the EndBASIC interpreter into your own programs.