eval-based interpreter in Stak Scheme

@raviqqe

July 21, 2024

Contents

• Stak Scheme
• Progress
• The eval-based interpreter
• Future work

Stak Scheme

• A bytecode compiler and virtual machine (VM) for Scheme
  • The compiler is written in Scheme.
  • The VM is written in Rust.
• It aims to support R7RS-small.

Progress

• An eval-based interpreter
  • Faster startup time
• The process-context library

The eval-based interpreter

The stak command

• A Stak Scheme interpreter
• cargo install stak

Previous architecture

1. AOT compile of source codes into bytecodes
2. Run the bytecodes on a VM

Current architecture

1. Run bytecodes of eval-based interpreter written in Scheme

Interpreter in Scheme

(import
  (scheme base)
  ; ...
  (scheme eval))

(define (main)
  (define program (open-input-file (list-ref (command-line) 1)))

  (do ()
    ((eof-object? (peek-char program))
      #f)
    (if (char-whitespace? (peek-char program))
      (read-char program)
      (eval (read program) (interaction-environment)))))

(main)

Demo

Future work

• Faster startup time
• Faster cargo install time
  • Build scripts?
• More compatibility
  • (scheme time) library

Summary

• Building an interpreter!