Progress in Stak Scheme

October 13, 2024

Contents

• Startup time optimization
• Tree shaking
• (scheme time) library

Startup time optimization

• Now, the Scheme interpreter written by Stak Scheme itself starts in ~200 ms on macOS!
• It's basically REPL without the print part.
  • It doesn't support define-library.
• Libraries and macros bundled in the interpreter was huge.
  • They are automatically compiled into the resulting bytecodes.
• Optimizing their data structures helped a lot.

Tree shaking

• (import (shake (scheme base))) imports only symbols used in the codes below.
• Not in R7RS
• It's technically the same as (import (only (scheme base) ...)) enumerating all used symbols.
• Definitions are not removed like JavaScript/TypeScript's tree shaking.

(import (shake (scheme base)))

(write-string "Hello, world!")

(scheme time) library

• Time procedures
  • current-jiffy
  • current-second
  • jiffies-per-second
• Implemented by Rust's std or libc

Triplet rib

• Previously, Stak Scheme had a quartet data structure of (type car cdr tag).
  • This is internally two 64-bit words.
  • type is a tag in a car pointer.
  • tag is a tag in a cdr pointer.
• But it is (car cdr tag).
• type and tag are merged into one.
• This should make the new bytecode encoding easier...

Others

• Adopting core::error

Future work

• Developing the new bytecode encoding takes time.
• Hopefully, it's done on the next meetup.
• We'll see...