171 lines
7.1 KiB
Markdown
171 lines
7.1 KiB
Markdown
# WAFER
|
|
|
|
**WebAssembly Forth Engine in Rust**
|
|
|
|
An optimizing Forth 2012 compiler targeting WebAssembly. WAFER JIT-compiles each word definition to a separate WASM module and executes it via [wasmtime](https://wasmtime.dev/).
|
|
|
|
## Highlights
|
|
|
|
- **200+ words** across 12 Forth 2012 word sets, all at **100% compliance**
|
|
- **Optimizing compiler** with 6 IR passes + stack-to-local promotion + consolidation
|
|
- **JIT compilation** — each `:` definition compiles to its own WASM module
|
|
- **Consolidation mode** — recompile all words into a single optimized WASM module
|
|
- **Interactive REPL** with line editing (rustyline)
|
|
|
|
## Installation
|
|
|
|
Requires [Rust](https://www.rust-lang.org/tools/install) 1.85+ (edition 2024).
|
|
|
|
```bash
|
|
cargo install --git https://github.com/ok2/wafer.git wafer
|
|
```
|
|
|
|
This installs the `wafer` binary to `~/.cargo/bin/`.
|
|
|
|
To install from a local checkout:
|
|
|
|
```bash
|
|
cargo install --path crates/cli
|
|
```
|
|
|
|
## Usage
|
|
|
|
```bash
|
|
# Interactive REPL (type BYE to exit)
|
|
wafer
|
|
|
|
# Run a Forth file
|
|
wafer program.fth
|
|
|
|
# Pipe input
|
|
echo ': SQUARE DUP * ; 7 SQUARE .' | wafer
|
|
|
|
# Consolidation: recompile all words into a single optimized WASM module
|
|
wafer --consolidate program.fth
|
|
|
|
# Consolidation with WASM output
|
|
wafer --consolidate -o output.wasm program.fth
|
|
```
|
|
|
|
**Example REPL session:**
|
|
|
|
```forth
|
|
: FIB DUP 2 < IF DROP 1 ELSE DUP 1 - RECURSE SWAP 2 - RECURSE + THEN ;
|
|
: FIBS 0 DO I FIB . LOOP ;
|
|
12 FIBS CR \ prints: 1 1 2 3 5 8 13 21 34 55 89 144
|
|
|
|
VARIABLE COUNTER 0 COUNTER !
|
|
: BUMP COUNTER @ 1 + COUNTER ! ;
|
|
BUMP BUMP BUMP COUNTER @ . \ prints: 3
|
|
```
|
|
|
|
## Building from source
|
|
|
|
```bash
|
|
git clone --recurse-submodules https://github.com/ok2/wafer.git
|
|
cd wafer
|
|
cargo build --workspace --release
|
|
```
|
|
|
|
If you already cloned without `--recurse-submodules`, fetch the Forth 2012 test suite with:
|
|
|
|
```bash
|
|
git submodule update --init
|
|
```
|
|
|
|
## Testing
|
|
|
|
```bash
|
|
# All tests (392 currently passing)
|
|
cargo test --workspace
|
|
|
|
# Forth 2012 compliance suite
|
|
cargo test -p wafer-core --test compliance
|
|
|
|
# Optimization benchmark report
|
|
cargo test -p wafer-core --test benchmark_report -- --nocapture --ignored
|
|
|
|
# Lints
|
|
cargo clippy --workspace
|
|
```
|
|
|
|
## Architecture
|
|
|
|
```
|
|
Forth Source -> Outer Interpreter -> IR -> [Optimize] -> WASM Codegen (wasm-encoder)
|
|
|
|
|
wasmtime instantiation
|
|
(shared memory + table)
|
|
```
|
|
|
|
- **Subroutine threading** via WASM function tables and `call_indirect`
|
|
- **JIT mode**: each new word compiles to a separate WASM module linked to shared memory/globals/table
|
|
- **IR-based pipeline** with 6 optimization passes (peephole, constant folding, strength reduction, DCE, tail call detection, inlining) plus stack-to-local promotion and consolidation
|
|
- **Dictionary**: linked-list word headers in simulated linear memory
|
|
|
|
## Project Structure
|
|
|
|
```
|
|
crates/
|
|
core/ wafer-core: dictionary, IR, codegen, optimizer, outer interpreter
|
|
cli/ wafer: CLI REPL, file execution, consolidation
|
|
web/ wafer-web: browser bindings (planned)
|
|
forth/ Bootstrap definitions loaded at startup
|
|
tests/ Forth 2012 compliance suite (git submodule)
|
|
```
|
|
|
|
## Forth 2012 Compliance
|
|
|
|
Tested against [Gerry Jackson's Forth 2012 test suite](https://github.com/gerryjackson/forth2012-test-suite). 12 of 14 word sets pass at 100%.
|
|
|
|
| Word Set | Status |
|
|
| ------------------ | --------------------------------------- |
|
|
| Core | **100%** (0 errors) |
|
|
| Core Extensions | **100%** (0 errors) |
|
|
| Double-Number | **100%** (0 errors) |
|
|
| Exception | **100%** (0 errors) |
|
|
| Facility | **100%** (0 errors) |
|
|
| Floating-Point | **100%** (0 errors) |
|
|
| Locals | **100%** (0 errors) |
|
|
| Memory-Allocation | **100%** (0 errors) |
|
|
| Programming-Tools | **100%** (0 errors) |
|
|
| Search-Order | **100%** (0 errors) |
|
|
| String | **100%** (0 errors) |
|
|
| File-Access | Not started (requires WASI integration) |
|
|
| Extended-Character | Not started |
|
|
|
|
## Implemented Words
|
|
|
|
Over 200 words are implemented across the following categories:
|
|
|
|
| Category | Words |
|
|
| ------------ | --------------------------------------------------------------------------------------------------------------- |
|
|
| Stack | `DUP DROP SWAP OVER ROT NIP TUCK 2DUP 2DROP 2SWAP 2OVER ?DUP PICK DEPTH` |
|
|
| Arithmetic | `+ - * / MOD /MOD NEGATE ABS MIN MAX 1+ 1- 2* 2/ */ */MOD M* UM* UM/MOD FM/MOD SM/REM S>D <# # #S #> HOLD SIGN` |
|
|
| Comparison | `= <> < > U< 0= 0< 0<> 0> WITHIN` |
|
|
| Logic | `AND OR XOR INVERT LSHIFT RSHIFT` |
|
|
| Memory | `@ ! C@ C! +! 2@ 2! HERE ALLOT , C, CELLS CELL+ CHARS CHAR+ ALIGNED ALIGN MOVE FILL CMOVE CMOVE>` |
|
|
| Control | `IF ELSE THEN DO LOOP +LOOP I J UNLOOP LEAVE BEGIN UNTIL WHILE REPEAT RECURSE EXIT` |
|
|
| Defining | `: ; VARIABLE CONSTANT VALUE CREATE DOES> IMMEDIATE DEFER` |
|
|
| I/O | `. U. .S CR EMIT SPACE SPACES TYPE ." S" ACCEPT` |
|
|
| Return stack | `>R R> R@` |
|
|
| System | `EXECUTE ' CHAR [CHAR] ['] DECIMAL HEX BASE STATE >IN >BODY ENVIRONMENT? SOURCE ABORT TRUE FALSE BL` |
|
|
| Compiler | `LITERAL POSTPONE [ ] EVALUATE ABORT"` |
|
|
| Parsing | `WORD FIND COUNT >NUMBER` |
|
|
| Exceptions | `CATCH THROW` |
|
|
| Double-cell | `D+ D- D. D.R DNEGATE DABS D= D< D0= D0< D>S 2CONSTANT 2VARIABLE 2LITERAL M+ M*/` |
|
|
| Strings | `COMPARE SEARCH SLITERAL REPLACES SUBSTITUTE UNESCAPE` |
|
|
| Floating-Pt | `F+ F- F* F/ FABS FNEGATE FSQRT FSIN FCOS FTAN FEXP FLOG FMIN FMAX` and 55+ more |
|
|
| Case | `CASE OF ENDOF ENDCASE` |
|
|
|
|
## Roadmap
|
|
|
|
- **File-Access word set** — requires WASI integration for file I/O
|
|
- **Extended-Character word set** — Unicode support
|
|
- **Browser target** — `wafer-web` crate with wasm-bindgen for a web REPL
|
|
- **Self-hosting** — minimal Rust kernel (~35 primitives), everything else in Forth
|
|
|
|
## License
|
|
|
|
MIT OR Apache-2.0
|