# 🪸 ReefVM

It's where Shrimp live.

## Quickstart

    bun install
    bun test

## Use it

Execute text bytecode:

    ./bin/reef examples/loop.reef

Validate bytecode:

    ./bin/validate examples/loop.reef

Run the simple debugger to see what the instructions are doing:

    ./bin/debug examples/loop.reef
    ./bin/debug -h examples/loop.reef

Interactive REPL for exploring instructions:

    ./bin/repl

Type opcodes interactively and see the stack and variables update in real-time.

Commands: `clear`, `reset`, `exit`.

## Features

- Stack operations (PUSH, POP, DUP)
- Arithmetic operations (ADD, SUB, MUL, DIV, MOD)
- Comparison operations (EQ, NEQ, LT, GT, LTE, GTE)
- Logical operations (NOT, AND/OR patterns with short-circuiting)
- Variable operations (LOAD, STORE) with **emoji and Unicode support** (💎 = 5)
- Control flow with **relative jumps** (JUMP, JUMP_IF_FALSE, JUMP_IF_TRUE, BREAK, CONTINUE)
- Array operations (MAKE_ARRAY, ARRAY_GET, ARRAY_SET, ARRAY_PUSH, ARRAY_LEN)
- Dictionary operations (MAKE_DICT, DICT_GET, DICT_SET, DICT_HAS)
- Function operations (MAKE_FUNCTION, CALL, TAIL_CALL, RETURN) with parameter binding
- Variadic functions with positional rest parameters (`...rest`)
- Named arguments (named) that collect unmatched named args into a dict (`@named`)
- Mixed positional and named arguments with proper priority binding
- Tail call optimization with unbounded recursion (10,000+ iterations without stack overflow)
- Exception handling (PUSH_TRY, PUSH_FINALLY, POP_TRY, THROW) with nested try/finally blocks and call stack unwinding
- Native function interop with auto-wrapping for native TypeScript types
- Native functions stored in scope, called via LOAD + CALL
- Native functions support `atXxx` parameters (e.g., `atOptions`) to collect unmatched named args
- Pass functions directly to `run(bytecode, { fnName: fn })` or `new VM(bytecode, { fnName: fn })`
- Call Reef functions from TypeScript with `vm.call(name, ...args)` with automatic type conversion

## Design Decisions

- Relative jumps: All JUMP instructions use PC-relative offsets instead of absolute addresses, making bytecode position-independent
- Truthiness: Only `null` and `false` are falsy (unlike JavaScript where `0`, `""`, etc. are also falsy)
- Short-circuiting via compiler: No AND/OR opcodes—compilers use JUMP patterns for proper short-circuit evaluation
- Variadic parameters: Functions can collect remaining positional arguments into an array using `...rest` syntax
- Named parameters: Functions can collect unmatched named arguments into a dict using `@named` syntax
- Argument binding priority: Named args bind to regular params first, with unmatched ones going to `@named`