ok2
b52b4a79ce
Core word set: 0 errors on Gerry Jackson's forth2012-test-suite/core.fr - Fix POSTPONE for non-immediate words via COMPILE, mechanism - Fix double-DOES> (WEIRD: pattern) with does-body scanning and runtime patching via _DOES_PATCH_ - Implement CATCH/THROW exception handling using wasmtime trap mechanism with stack pointer save/restore - 232 tests passing
66 lines
2.6 KiB
Markdown
66 lines
2.6 KiB
Markdown
# WAFER Project Conventions
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## What is WAFER?
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WAFER (WebAssembly Forth Engine in Rust) is an optimizing Forth 2012 compiler targeting WebAssembly. Currently a working Forth system with 70+ words and JIT compilation.
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## Architecture
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- Each Forth word compiles to its own WASM module via `wasm-encoder`
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- Modules share memory, globals (dsp/rsp), and a function table via wasmtime imports
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- IR-based compilation: Forth -> `Vec<IrOp>` -> WASM codegen -> wasmtime instantiation
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- Dictionary: linked-list in a `Vec<u8>` buffer simulating WASM linear memory
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- Primitives: either IR-based (compiled to WASM) or host functions (Rust closures in wasmtime)
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## Key Files
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- `crates/core/src/outer.rs` -- ForthVM: the main runtime, outer interpreter, compiler, all primitives
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- `crates/core/src/codegen.rs` -- IR-to-WASM translation, module generation, wasmtime execution tests
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- `crates/core/src/dictionary.rs` -- Dictionary data structure with create/find/reveal
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- `crates/core/src/ir.rs` -- IrOp enum (the intermediate representation)
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- `crates/core/src/memory.rs` -- Memory layout constants (stack regions, dictionary base, etc.)
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- `crates/cli/src/main.rs` -- CLI REPL with rustyline
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## Adding a New Word
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**IR primitive** (simple stack/arithmetic/logic -- preferred when possible):
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```rust
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self.register_primitive("WORD_NAME", false, vec![IrOp::Dup, IrOp::Mul])?;
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```
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**Host function** (needs Rust logic -- I/O, dictionary manipulation, complex stack access):
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```rust
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let func = Func::new(&mut self.store, func_type.clone(), move |mut caller, _params, _results| {
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// manipulate memory/globals directly
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Ok(())
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});
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self.register_host_primitive("WORD_NAME", false, func)?;
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```
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**Special interpreter token** (defining words like VARIABLE, CONSTANT, CREATE):
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Handle in `interpret_token_immediate()` or `compile_token()` as a special case.
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## Code Style
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- `cargo fmt --all` and `cargo clippy --workspace` must pass with no warnings
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- Every public function needs a doc comment
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- Use `thiserror` for error types in core crate, `anyhow` for CLI
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- Prefer returning `Result` over panicking
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## Testing
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- Run `cargo test --workspace` before committing (currently 185 tests)
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- Forth 2012 compliance: `cargo test -p wafer-core --test compliance`
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- Test helper in outer.rs: `eval_output("forth code")` returns printed output as String
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- Test helper: `eval_stack("forth code")` returns data stack as Vec<i32>
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## Key Principles
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1. Correctness first, performance second
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2. Maximize Forth, minimize Rust (self-hosting goal -- not yet started)
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3. Test-driven: if it's not tested, it doesn't work
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4. Every word set at 100% compliance before moving to the next
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5. Never break existing tests
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