hakorune/docs/guides/user-macros.md

User Macros (MacroBoxSpec) — Phase 2

Status: PoC complete; PyVM sandbox route wired. This guide explains how to author and run user macros in Nyash.

Quickstart

• Register user macros (recommended minimal env):
  • NYASH_MACRO_ENABLE=1
  • NYASH_MACRO_PATHS=apps/macros/examples/echo_macro.nyash
• Run your program as usual (macro expansion happens once before MIR):
  • ./target/release/nyash --backend vm apps/tests/ternary_basic.nyash

Environment overview (recommended minimal set)

• NYASH_MACRO_ENABLE=1（既定ON）
• NYASH_MACRO_PATHS=...（カンマ区切りのNyashマクロファイル）
• NYASH_MACRO_STRICT=1（既定: 厳格）
• NYASH_MACRO_TRACE=0|1（開発用トレース）

Backward compat (deprecated)

• NYASH_MACRO_BOX_NY=1 + NYASH_MACRO_BOX_NY_PATHS=... → 今後は NYASH_MACRO_PATHS を使ってね

Philosophy

• Hybrid approach: built-in (Rust) for minimal/core derives; user macros in Nyash (PyVM) for flexibility.
• Deterministic, sandboxed execution: default denies IO/NET/ENV.
• Unified interface: AST JSON v0 + MacroCtx. Expansion occurs pre-MIR.

MacroCtx (MVP)

• Rust側に最小の MacroCtx と MacroCaps を用意（将来のAPI統合のため）。
• フィールド/メソッド（MVP）:
  • MacroCtx::from_env() → 環境からcapabilitiesを組み立て
  • ctx.gensym(prefix) → 衛生識別子生成
  • ctx.report(level, message) → 開発用レポート（標準エラー）
  • ctx.get_env(key) → 環境取得（NYASH_MACRO_CAP_ENV=1 のときのみ）
• 実行契約（PoC）：ランナーは expand(json, ctx) を優先し、失敗した場合は expand(json) にフォールバックします（後方互換）。

Authoring a Macro

Create a Nyash file that defines MacroBoxSpec with a static expand(json[, ctx]) returning a JSON string (AST JSON v0):

static box MacroBoxSpec {
  static function expand(json, ctx) {
    // json: string (AST JSON v0)
    // ctx:  string (JSON; {caps:{io,net,env}} MVP). Optional for backward compatibility.
    // return: string (AST JSON v0)
    return json  // identity for MVP
  }
}

Example (repo): apps/macros/examples/echo_macro.nyash.

Editing template (string literal uppercasing)

• Example: apps/macros/examples/upper_string_macro.nyash
• Behavior: if a string literal value starts with UPPER:, the suffix is uppercased.
  • Input: print("UPPER:hello") → Output: print("HELLO")

Running your Macro

Register and run via env (simple):

export NYASH_MACRO_ENABLE=1
export NYASH_MACRO_PATHS=apps/macros/examples/echo_macro.nyash

# Run your program (macro expansion happens before MIR)
./target/release/nyash --backend vm apps/tests/ternary_basic.nyash

Self‑host path（NYASH_USE_NY_COMPILER=1）での前展開（開発用）

NYASH_USE_NY_COMPILER=1 \
NYASH_MACRO_SELFHOST_PRE_EXPAND=1 \
NYASH_VM_USE_PY=1 \
./target/release/nyash --backend vm apps/tests/ternary_basic.nyash

Notes: 現状は PyVM ルートのみ対応。NYASH_VM_USE_PY=1 が必須。

CLI プロファイル（推奨）

• --profile dev（既定相当: マクロON/厳格ON）
• --profile lite（マクロOFFの軽量モード）
• --profile ci|strict（マクロON/厳格ON）
  • 例: ./target/release/nyash --profile dev --backend vm apps/tests/ternary_basic.nyash

Notes

• Built-in child route (stdin JSON -> stdout JSON) remains available when NYASH_MACRO_BOX_CHILD_RUNNER=0.
• Strict mode: NYASH_MACRO_STRICT=1 (default) fails build on macro child error/timeout; set 0 to fallback to identity.
• Timeout: NYASH_NY_COMPILER_TIMEOUT_MS (default 2000).

Testing

• Smoke: tools/test/smoke/macro/macro_child_runner_identity_smoke.sh
• Golden (identity): tools/test/golden/macro/identity_user_macro_golden.sh
• Golden (upper string): tools/test/golden/macro/upper_string_user_macro_golden.sh
• Golden (array prepend 0): tools/test/golden/macro/array_prepend_zero_user_macro_golden.sh
• Golden (map insert tag): tools/test/golden/macro/map_insert_tag_user_macro_golden.sh
• Negative (timeout strict fail): tools/test/smoke/macro/macro_user_timeout_strict_fail.sh
• Negative (invalid JSON strict fail): tools/test/smoke/macro/macro_user_invalid_json_strict_fail.sh
• Negative (invalid JSON non‑strict identity): tools/test/smoke/macro/macro_user_invalid_json_nonstrict_identity.sh

Array/Map editing examples

• Array prepend zero: apps/macros/examples/array_prepend_zero_macro.nyash
  • Transforms every {"kind":"Array","elements":[...]} into one with a leading 0 literal element.
  • Example input: print([1, 2]) → Expanded: elements [0, 1, 2].
• Map insert tag: apps/macros/examples/map_insert_tag_macro.nyash
  • Transforms every {"kind":"Map","entries":[...]} by inserting the first entry {k:"__macro", v: "on"}.
  • Example input: print({"a": 1}) → Expanded entries: [{"__macro":"on"}, {"a":1}].

Inspect Expanded AST

./target/release/nyash --dump-expanded-ast-json apps/tests/ternary_basic.nyash

Outputs AST JSON v0 after expansion; use this for golden comparison.

AST JSON v0 Schema

See docs/reference/ir/ast-json-v0.md for the minimal schema used in Phase 2.

Troubleshooting

• Child timeout: increase NYASH_NY_COMPILER_TIMEOUT_MS or simplify macro code; strict mode fails fast.
• Invalid JSON from child: ensure expand(json) returns a valid AST JSON v0 string.
• No changes observed: confirm your macro is registered and the runner route is enabled.
• Capability denied: set caps explicitly（デフォルトは全OFF）
  • NYASH_MACRO_CAP_IO=1 → IO系Box（File/Path/Dir）許可
  • NYASH_MACRO_CAP_NET=1 → NET系Box（HTTP/Socket）許可
  • NYASH_MACRO_CAP_ENV=1 → MacroCtx.get_env 許可（将来拡張）

Roadmap

• MacroCtx capabilities (io/net/env) expressed via nyash.toml per-macro.
• Diagnostics: JSONL tracing (NYASH_MACRO_TRACE_JSONL) and span/source maps.
• Golden tests for expanded JSON; strict mode as default.

Capabilities (io/net/env)

Purpose: restrict side‑effects and ensure deterministic macro expansion.

• Default: all OFF (io=false, net=false, env=false)
• Behavior:
  • io=false → no FileBox/FS access inside macro; AST JSON only
  • net=false → no Http/Socket inside macro
  • env=false → MacroCtx.getEnv disabled; child inherits scrubbed env
• Planned configuration (nyash.toml): see docs/reference/macro/capabilities.md
• PoC mapping: child is always NYASH_VM_USE_PY=1, NYASH_DISABLE_PLUGINS=1, timeout via NYASH_NY_COMPILER_TIMEOUT_MS

Top-level static MacroBoxSpec (safety)

• 既定では無効（NYASH_MACRO_TOPLEVEL_ALLOW=0）。Box宣言なしで static function MacroBoxSpec.expand を受理したい場合は --macro-top-level-allow を指定してください。