139 lines
6.0 KiB
Markdown
139 lines
6.0 KiB
Markdown
# Macro System (Phase 16) — Quickstart
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Status: MVP available behind environment gates (default OFF). This page describes how to enable and use the initial features (derive, test runner, expansion dump) and the developer‑facing Pattern/Quote API preview.
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## Enabling/disabling macros
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- Default: ON
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- Disable: `NYASH_MACRO_DISABLE=1` or `NYASH_MACRO_ENABLE=0|false|off`
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- Debug trace: `NYASH_MACRO_TRACE=1`
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- CLI shortcut for debug: `--expand` (prints pre/post AST, and sets trace)
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## Derive (MVP)
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- Provided derives: `Equals`, `ToString`
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- Control via env:
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- `NYASH_MACRO_DERIVE=Equals,ToString` (default when unset)
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- `NYASH_MACRO_DERIVE_ALL=1` (force all derives)
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- Behavior:
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- Injects `equals(__ny_other)` and `toString()` into Box declarations when not already present.
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- Public-only: derives operate on public fields only (Philosophy: Box independence / loose coupling).
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- No changes to MIR instruction set; expansion happens on AST, then compiled as usual.
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Example
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```
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NYASH_MACRO_ENABLE=1 ./target/release/nyash --backend vm apps/APP/main.nyash
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```
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## Test runner (MVP)
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- CLI: `--run-tests` → enable macro engine and inject a test harness main
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- Discovery targets:
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- Top‑level functions with names `test_*`
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- Box static/instance methods `test_*`
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- Filtering: `--test-filter SUBSTR` or `NYASH_TEST_FILTER=SUBSTR`
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- Entry policy when a main exists:
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- `--test-entry wrap` → rename original `main` to `__ny_orig_main`, run tests then call original
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- `--test-entry override` → replace entry with test harness only
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- Force apply even if a main exists: `NYASH_TEST_FORCE=1`
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- Return policy in wrap mode:
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- `--test-return {tests|original}` or `NYASH_TEST_RETURN`
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- `tests` (default): harness returns number of failed tests
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- `original`: return the original main result (tests still run)
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- Parameterized tests (MVP): `NYASH_TEST_ARGS_DEFAULTS=1` injects integer `0` defaults for each parameter (static/instance)
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- Exit code: number of failed tests (0 = green)
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Examples
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```
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# run all tests in a file
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./target/release/nyash --run-tests apps/tests/my_tests.nyash
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# filter + wrap entry + default arg injection
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NYASH_MACRO_ENABLE=1 NYASH_TEST_ARGS_DEFAULTS=1 \
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./target/release/nyash --run-tests --test-filter http --test-entry wrap apps/tests/my_tests.nyash
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```
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## Expansion dump
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```
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./target/release/nyash --expand --dump-ast apps/tests/ternary_basic.nyash
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```
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Shows pre/post expansion AST (debug only).
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## Core Normalization (always-on when macros enabled)
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Certain language sugars are normalized before MIR across all runners when the macro gate is enabled. These are not user macros and do not require any registration:
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- for sugar → Loop
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- `for(fn(){ init }, cond, fn(){ step }, fn(){ body })`
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- Emits: `init; loop(cond){ body; step }`
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- `init/step` also accept a single Assignment or Local instead of `fn(){..}`.
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- foreach sugar → Loop
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- `foreach(array_expr, "x", fn(){ body_with_x })`
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- Expands into an index-based loop with `__ny_i`, and substitutes `x` with `array_expr.get(__ny_i)` inside body.
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Normalization order (within the core pass):
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1) for/foreach → 2) match(PeekExpr) → 3) loop tail alignment (carrier-like ordering; break/continue segments supported).
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Notes:
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- Backward-compat function names `ny_for` / `ny_foreach` are also accepted but `for` / `foreach` are preferred.
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- This pass is part of the language pipeline; it is orthogonal to user-defined macros.
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## Developer API (preview)
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- Pattern/Quote primitives are available to bootstrap macro authorship.
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- TemplatePattern:
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- Bind placeholders using `$name` inside a template AST.
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- OrPattern: alternation of templates.
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- Variadic `$...name` supported at any position inside call/array argument lists; binds the variable-length segment to a pseudo list (`ASTNode::Program`).
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- Unquote:
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- Replace `$name` with the bound AST.
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- Splice `$...name` into call/array argument lists.
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- Array/Map nodes participate in pattern/unquote (map keys must match literally; values can bind via `$name`).
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## MacroCtx (PoC)
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User macros executed via the PyVM sandbox receive a second argument `ctx` in `expand(json, ctx)`:
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- Shape (string): `{ "caps": { "io": bool, "net": bool, "env": bool } }`
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- Policy: all caps default to false. The sandbox disables plugins and exposes a minimal Box API.
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- Do not print to stdout from macros: the child process stdout is reserved for the expanded JSON.
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- For diagnostics use stderr in the future; for now prefer silent operation or trace via the parent process.
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Example (identity):
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```
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static box MacroBoxSpec {
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name() { return "MacroCtxDemo" }
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expand(json, ctx) { return json }
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}
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```
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### JSON test args (advanced)
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For `--run-tests`, you can supply per-test arguments and instance construction details via `NYASH_TEST_ARGS_JSON`.
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Shapes:
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- Simple list (as before): `{ "test_name": [1, "s", true], "Box.method": [ 0, 1 ] }`
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- Detailed object:
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- `{ "Box.method": { "args": [ ... ], "instance": { "ctor": "new|birth", "args": [ ... ], "type_args": ["T", "U"] } } }`
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- Typed values inside args:
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- `{ "i": 1 }`, `{ "f": 1.2 }`, `{ "s": "x" }`, `{ "b": true }`, `null`
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- Arrays/Maps as value: `{ "array": [1, 2, 3] }`, `{ "map": { "k": 1, "k2": {"s":"v"} } }`
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- Call/method/var literals: `{ "call": "fn", "args": [...] }`, `{ "method": "m", "object": {"var":"obj"}, "args": [...] }`, `{ "var": "name" }`
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Diagnostics:
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- When JSON cannot be mapped or arity mismatches, warnings are printed with `[macro][test][args]` and the specific test may be skipped unless `NYASH_TEST_ARGS_DEFAULTS=1` is set.
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Notes
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- Textual `quote(code)` is supported as a convenience via the existing parser, but `$name` placeholders should be built in AST templates directly.
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- This API will evolve; treat as experimental until the stable `macro_box` interface is finalized.
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## Expansion Safety (Depth/Cycle)
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- The macro engine applies a bounded number of expansion passes and stops on fixpoint.
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- Environment tuning:
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- `NYASH_MACRO_MAX_PASSES` (default 32)
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- `NYASH_MACRO_CYCLE_WINDOW` (default 8) — detect cycles across recent states
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- `NYASH_MACRO_TRACE=1` — pass-by-pass logging
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