BASIC Interpreter

A Dartmouth BASIC language clone, interpreter REPL and "Transpiler" to Go, written in Go Lang.

disclaimer: 80 % Vibe coded, 10% love of programming, 10% coffee.

Vibe coding and Manual coding

• Phase 1 BASIC REPL in GoLang: AbacusAI-- Claude Sonnet 4.5; couldn't quite get it right, but laid the ground work for the REPL.

• Phase 2 BASIC and Troubleshooting: AbacusAI Claude Sonnet 4.5; coding BASIC and troubleshooting in Go

• Phase 3 GoLang and Troubleshooting: GPT-5.1 Codex, mostly built the compiler, not happy with this but it works.

Features

• Classic BASIC syntax with line numbers
• Supported statements:
  • PRINT - Output text and expressions
  • LET - Variable assignment
  • IF...THEN...ELSE - Conditional execution
  • FOR...TO...STEP...NEXT - Loops
  • GOTO - Jump to line number
  • GOSUB/RETURN - Subroutines
  • INPUT - User input
  • DIM - Array declaration
  • REM - Comments
  • END - End program
• Operators: +, -, *, /, MOD, <, >, <=, >=, ==, <>, AND, OR, NOT
• Data types: Numbers and Strings
• Arrays with indexing

Building

go build -o basic main.go

Usage

Run a BASIC file:

./basic examples/hello.bas

Transpile a BASIC file to Go

./basic -compile hello.go examples/hello.bas
go run hello.go

Compile a BASIC file to a single executeable, 2 step procedure

./basic -compile hello.go examples/hello.bas && go build -o hello hello.go

Interactive REPL:

./basic

REPL commands:

• RUN - Execute the program
• LIST - Show the program
• CLEAR or NEW - Clear the program
• EXIT or QUIT - Exit the interpreter
• SAVE <filename.bas> - Save code to disk
• LOAD <filename.bas> - Load code from disk
• DELETE n - Deletes a line number

Examples

Hello World

10 PRINT "Hello, World!"
20 END

For Loop

10 FOR I = 1 TO 10
20 PRINT I
30 NEXT I
40 END

Input and Conditionals

10 INPUT "Enter your age: "; AGE
20 IF AGE >= 18 THEN PRINT "Adult" ELSE PRINT "Minor"
30 END

Example Programs

See the examples/ directory for more sample programs:

• hello.bas - Hello World
• fibonacci.bas - Fibonacci sequence
• guess.bas - Number guessing game
• multiply.bas - Multiplication table
• gosub.bas - Subroutine example