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fb1395c740
- DOES> with split-compilation for defining words (CREATE , DOES> @ pattern) - EVALUATE for string interpretation - Double-cell: M* UM* UM/MOD FM/MOD SM/REM S>D */ */MOD - Parsing: WORD FIND COUNT >NUMBER >IN STATE - Memory: CMOVE CMOVE> - Compile-time: ABORT" S" (compile mode) - 219 tests passing, ~90% Core word set coverage - Update docs to reflect current implementation
142 lines
4.6 KiB
Markdown
142 lines
4.6 KiB
Markdown
# WAFER
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**WebAssembly Forth Engine in Rust**
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An optimizing Forth 2012 compiler targeting WebAssembly.
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## Status
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WAFER is a working Forth system. It JIT-compiles each word definition to a separate WASM module and executes via `wasmtime`. 185 tests passing.
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**Working features:**
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- Colon definitions with full control flow (IF/ELSE/THEN, DO/LOOP/+LOOP, BEGIN/UNTIL, BEGIN/WHILE/REPEAT)
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- 70+ words: stack, arithmetic, comparison, logic, memory, I/O, defining words, system
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- Recursion (RECURSE), nested control structures, loop counters (I, J)
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- VARIABLE, CONSTANT, CREATE
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- Number bases (HEX, DECIMAL), number prefixes ($hex, #dec, %bin)
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- Comments (backslash, parentheses), string output (." ...)
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- Interactive REPL with line editing
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**Example session:**
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```forth
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: FIB DUP 2 < IF DROP 1 ELSE DUP 1 - RECURSE SWAP 2 - RECURSE + THEN ;
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: FIBS 0 DO I FIB . LOOP ;
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12 FIBS CR \ prints: 1 1 2 3 5 8 13 21 34 55 89 144
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VARIABLE COUNTER 0 COUNTER !
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: BUMP COUNTER @ 1 + COUNTER ! ;
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BUMP BUMP BUMP COUNTER @ . \ prints: 3
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```
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## Goals
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- **Full Forth 2012 compliance** -- all word sets, 100% test suite pass rate
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- **Optimizing compiler** -- constant folding, inlining, peephole optimization, stack-to-local promotion
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- **Multi-typed stack** -- type inference uses WASM's native typed stack when possible
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- **Self-hosting** -- minimal Rust kernel (~35 primitives), everything else in WAFER Forth
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- **Consolidation mode** -- recompile all JIT words into a single optimized WASM module
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## Architecture
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```
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Forth Source -> Outer Interpreter -> IR -> [Optimize] -> WASM Codegen (wasm-encoder)
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wasmtime instantiation
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(shared memory + table)
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```
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- **Subroutine threading** via WASM function tables and `call_indirect`
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- **JIT mode**: each new word compiles to a separate WASM module linked to shared memory/globals/table
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- **IR-based pipeline** enables future optimization passes before WASM emission
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- **Dictionary**: linked-list word headers in simulated linear memory
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## Building
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```bash
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cargo build --workspace
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```
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## Running
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```bash
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# Interactive REPL
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cargo run -p wafer
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# Run a Forth file
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cargo run -p wafer -- file.fth
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# Pipe input
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echo ': SQUARE DUP * ; 7 SQUARE .' | cargo run -p wafer
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```
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## Testing
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```bash
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# All tests (185 currently passing)
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cargo test --workspace
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# Forth 2012 compliance dashboard
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cargo test -p wafer-core --test compliance
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# Lints
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cargo clippy --workspace
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```
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## Project Structure
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```
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crates/
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core/ wafer-core: dictionary, IR, codegen (wasm-encoder), outer interpreter
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cli/ wafer: CLI REPL and file execution (wasmtime, rustyline)
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web/ wafer-web: browser bindings (planned)
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forth/ Standard library in WAFER Forth (planned, currently stubs)
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tests/ Forth 2012 compliance suite (gerryjackson/forth2012-test-suite submodule)
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```
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## Implemented Words
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### Core (Forth 2012 Section 6.1) -- In Progress
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| Category | Words |
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|----------|-------|
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| Stack | `DUP DROP SWAP OVER ROT NIP TUCK 2DUP 2DROP 2SWAP 2OVER ?DUP PICK DEPTH` |
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| Arithmetic | `+ - * / MOD /MOD NEGATE ABS MIN MAX 1+ 1- 2* 2/ */ */MOD M* UM* UM/MOD FM/MOD SM/REM S>D` |
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| Comparison | `= <> < > U< 0= 0< 0<> 0> WITHIN` |
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| Logic | `AND OR XOR INVERT LSHIFT RSHIFT` |
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| Memory | `@ ! C@ C! +! HERE ALLOT , C, CELLS CELL+ CHARS CHAR+ ALIGNED ALIGN MOVE FILL CMOVE CMOVE>` |
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| Control | `IF ELSE THEN DO LOOP +LOOP I J UNLOOP LEAVE BEGIN UNTIL WHILE REPEAT RECURSE EXIT` |
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| Defining | `: ; VARIABLE CONSTANT CREATE DOES> IMMEDIATE` |
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| I/O | `. U. .S CR EMIT SPACE SPACES TYPE ." S" ACCEPT` |
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| Return stack | `>R R> R@` |
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| System | `EXECUTE ' CHAR [CHAR] ['] DECIMAL HEX BASE STATE >IN >BODY ENVIRONMENT? SOURCE ABORT TRUE FALSE BL` |
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| Compiler | `LITERAL POSTPONE [ ] EVALUATE ABORT"` |
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| Parsing | `WORD FIND COUNT >NUMBER` |
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### Not Yet Implemented
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Remaining words needed for full Core compliance: `#` `#>` `#S` `<#` `HOLD` `SIGN` (pictured numeric output), `2!` `2@` `2>R` `2R>` `2R@`, and edge cases in existing words.
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## Compliance Status
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Targeting 100% Forth 2012 compliance via [Gerry Jackson's test suite](https://github.com/gerryjackson/forth2012-test-suite).
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| Word Set | Status |
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|----------|--------|
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| Core | In progress (~90%) |
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| Core Extensions | Pending |
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| Double-Number | Pending |
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| Exception | Pending |
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| Facility | Pending |
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| File-Access | Pending |
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| Floating-Point | Pending |
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| Locals | Pending |
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| Memory-Allocation | Pending |
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| Programming-Tools | Pending |
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| Search-Order | Pending |
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| String | Pending |
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| Extended-Character | Pending |
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## License
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MIT OR Apache-2.0
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