Array-based Lisp?

@raviqqe

Daydreaming about an array-based Lisp language...

Progress so far

• https://github.com/raviqqe/arachne
• Single-word runtime value with NaN boxing
• Reference counting GC
• Interpreter
  • AST-based implementation of primitive operations
  • Bytecode VM
    • Work in progress...

Virtual machine

• Stack machine

Instructions

nil, float64, symbol, local, get, set, length, add, subtract, multiply, divide, call, closure, equal, array, drop, dump, jump, return

• nil, float64, symbol: Pushes a constant.
• local: Gets a value of a local variable.
• get: Gets a value from an array.
• set: Sets a value to an array.

Types

• Float64
• Symbol
• Function
• Array
• Nil
  • () = 0 = false

Design decisions

• Operand evaluation order & argument order in a stack
  • Scheme doesn't specify its operand evaluation order in its specification.
• Tight or loose coupling between bytecode compiler and VM
  • Is it ok to embed runtime values into bytecodes?
  • Do we want to save bytecodes of modules in a file system?

Next tasks...

• call instruction
• Closures

Summary

• Daydreaming a language is fun.

Ribbit

• https://github.com/udem-dlteam/ribbit
• AOT compiler + RVM
• Everything is a rib.
  • Rib is a three-word data structure.

Objects

Bytecodes

• You can GC bytecodes!