feat: draft new spec#2
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- 0011: rewrite error handling around `throws E` clause, `throw` expr, `?` propagation, and `try`/`catch`; drop built-in Result - 0008: add `throws E` clause to function types - 0009: clarify throws is a separate channel from the effect row - 0003/0005/0010: align examples with throws-based errors - rename 0010-typed-ir.md to 0012-typed-ir.md to resolve number clash
Specify the boundary where capability effects (0009) are resolved by the runtime. Platform functions are a language-defined interface; Emela declares them with `extern fn` (matching the interface) and holds no implementation, each backend provides a subset, and an executable that requires a platform function the target does not provide is rejected. Cross-reference from 0009 and list 0013 in the README drafts.
- 0001: define Never as the bottom type — no value, assignable to any expected type, and the type of throw/panic - 0011: note throws Never is equivalent to non-throwing, and require the entrypoint main's throws to be Never
Snapshot the in-progress generics draft and list it in the README drafts.
Specify the language primitives needed to write `to_string` in pure Emela:
- 0015: `if cond { } else { }` as an expression (else required, branches unify).
- 0016: `/` and `%` (Int truncates toward zero, `%` Int-only, division by zero
traps; Float `/` is real division).
- 0017: a `Char` type with `'x'` literals, `++` string concatenation, and the
pure conversions `Char.from_code` / `String.from_char` (language built-ins,
not platform functions). WASM `String.from_char` is ASCII-only for now.
Index them in the README.
Imported functions become callable by any suffix of their import path (bare, leaf-qualified, or fully qualified). Multiple imports may bind the same bare name; collisions are resolved at the use site, not at import time. Specifies the resolution rules R1–R6 and resolution precedence, and extends spec 0010.
Define the `|>` pipeline operator: `lhs |> f(a, b)` inserts the left operand as the first argument (`f(lhs, a, b)`), lowest precedence, left-associative, with a trailing `?` applied after insertion. It is a pure desugaring to a call, so the IR and backends are unchanged (Compilation Notes).
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Pull request overview
This PR refreshes and reorganizes the Emela language specification drafts to better match the direction of targeting WASM/WAMR, replacing older monolithic drafts with a newer, renumbered set of smaller specs.
Changes:
- Added a new sequence of draft specs (0000–0019) covering core semantics, effects/throws, modules/imports, typed IR, runtime/platform boundary, and new surface features (if-expression, division/remainder, qualified calls, pipeline operator).
- Removed older draft specs that are superseded by the new structure (e.g., prior minimal core, imports, function values, pipeline syntax, toolchain/package resolution, etc.).
- Updated
README.mdto reflect the new “Current Drafts” list.
Reviewed changes
Copilot reviewed 35 out of 35 changed files in this pull request and generated 10 comments.
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| File | Description |
|---|---|
| specs/0019-pipeline-operator.md | Introduces the ` |
| specs/0018-qualified-imports-and-calls.md | Defines qualified import suffix resolution and disambiguation at call sites. |
| specs/0017-char-and-string-concatenation.md | Adds Char, char literals, ++, and minimal Char/String conversions plus backend notes. |
| specs/0016-integer-division-and-remainder.md | Specifies / and % semantics for Int/Float including trap behavior notes. |
| specs/0015-if-expression.md | Defines if as an expression with typing/effect rules and lowering notes. |
| specs/0014-generic-functions.md | Defines named generic functions, parametricity constraints, and monomorphization. |
| specs/0013-platform-functions-and-runtime-provision.md | Defines the platform-function boundary and runtime provisioning contract for effects. |
| specs/0013-generic-functions.md | Removes the older generic-functions draft (superseded by 0014). |
| specs/0012-typed-ir.md | Introduces typed IR requirements, examples, and core IR concepts. |
| specs/0012-toolchain-and-package-resolution.md | Removes the older toolchain/package-resolution draft (scope shifted by the reorg). |
| specs/0011-pipeline-syntax.md | Removes the older pipeline-syntax draft (superseded by 0019). |
| specs/0011-error-handling.md | Adds a new error-handling spec (throws/throw/?/try-catch/panic and lowering notes). |
| specs/0010-modules-imports-visibility.md | Adds a minimal modules/imports/visibility spec as the base for later import extensions. |
| specs/0010-function-values.md | Removes the older function-values draft (replaced by the new core structure). |
| specs/0009-type-annotations.md | Removes the older type-annotations draft (replaced by the new core structure). |
| specs/0009-effect-semantics.md | Adds the effect semantics baseline and built-in effect set; links to platform-function boundary. |
| specs/0008-imports.md | Removes the older imports draft (replaced by 0010 + 0018 direction). |
| specs/0008-function-types-with-effects.md | Defines function type shape including throws/uses clauses and examples. |
| specs/0007-generic-types.md | Removes the older generic-types draft (replaced by the new core structure). |
| specs/0007-array-and-strings.md | Adds an approved baseline spec for arrays/strings and their high-level semantics. |
| specs/0006-result-type.md | Removes the older result-type draft (error model shifted to throws/Option). |
| specs/0006-records.md | Adds a records spec draft with basic syntax and access examples. |
| specs/0005-enum-types.md | Removes the older enum-types draft (replaced by approved enum/match spec). |
| specs/0005-enum-and-match-expression.md | Adds an approved enum + match spec, including guards and IR lowering sketch. |
| specs/0004-struct-types.md | Removes the older struct-types draft (replaced by records + new core structure). |
| specs/0004-blocks-and-expression-semantics.md | Adds an approved baseline for blocks and expression-oriented semantics. |
| specs/0003-platform-capabilities.md | Removes the older platform-capabilities draft (replaced by effects + platform functions model). |
| specs/0003-function-definitions-and-calls.md | Adds core function/call semantics including evaluation order, recursion, and function values. |
| specs/0002-traits-and-operators.md | Removes the older traits/operators draft (explicitly deferred per design principles). |
| specs/0002-binding-and-mutation.md | Adds an approved baseline for immutable bindings and let. |
| specs/0001-effect-system.md | Removes the older effect-system draft (replaced by 0009 + 0013 direction). |
| specs/0001-core-values-and-types.md | Adds core values/types draft including heap-vs-primitive model and Never. |
| specs/0000-minimal-core-language.md | Removes the older minimal-core draft (replaced by the new spec set). |
| specs/0000-language-design-principles.md | Adds an approved high-level principles document framing the reorg. |
| README.md | Updates the “Current Drafts” list to match the new spec set. |
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| ## 0000: Language Design Principles | |||
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| State: Approved | |||
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| ## 0001: Core Values and Types | |||
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| State: Draft | |||
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| ### String | ||
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| 文字単位は `byte`． |
| ``` | ||
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| ```text | ||
| fn loadUser(id: UserId) -> User effects { db } { |
| io.write_stderr : (String) -> Unit uses { io } | ||
| ``` | ||
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| 将来，0017 の標準 capability に合わせて `clock.now`，`random.int`，`fs.read` 等を追加する（本仕様を supersede せず拡張する）． |
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| - **IR**: platform 関数の呼び出しは，通常の関数呼び出しとは区別された専用ノードとして typed IR に保持する（0012，effect 注釈を保つ）． | ||
| - **JS backend**: backend が platform 関数の実体を提供する．既定ではランタイムオブジェクトを生成物に同梱する（例 `__rt["io.write_stdout"] = s => process.stdout.write(s)`）．ホストが実体を注入する形にしてもよい． | ||
| - **WASM/WAMR backend**: platform 関数は WASI / host import に lower する．ユーザーには WASI を直接見せない (0016)．文字列はランタイム管理の linear memory 表現で受け渡す (0007, 0015)．生成モジュールが import するのは WASI の関数のみとし，未提供 capability はロード時にも解決不能となる． |
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| ### Open Questions | ||
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| - registry の初期セットの確定（`io` と `log` を分けるか，`io.write_stdout` を `io` と `log` のどちらの capability にするか，0017 と整合）． |
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| - `Char` は実行時にはコードポイントの整数（WebAssembly では `i32`，JavaScript では number）として表現する． | ||
| - JavaScript (Tier 2): `Char.from_code` は恒等，`String.from_char` は `String.fromCodePoint(c)`，`++` は `a + b`．全コードポイントを正しく扱う． | ||
| - WebAssembly (Tier 1): `String` は線形メモリ上の `[len: i32][utf8 bytes]`（0013/0015）．`++` は `alloc(4 + len1 + len2)` ＋ 長さ書込み ＋ `memory.copy` ×2．`String.from_char` は **当面 ASCII（コードポイント < 128）の1バイトのみ**を符号化する（多バイト UTF-8 符号化は後続）． |
| - **P2（第一引数挿入）**: 右辺が呼び出し式 `f(a1, …, an)`（n ≥ 0）のとき，`lhs |> f(a1, …, an)` は `f(lhs, a1, …, an)` と等価である (MUST)．callee `f` は任意の式でよい． | ||
| - **P3（bare 右辺）**: 右辺が呼び出し式でない式 `e` のとき，`lhs |> e` は `e(lhs)` と等価である (MUST)．`e` は関数値に評価されなければならない（さもなくば型エラー）． | ||
| - **P4（末尾 `?`）**: 右辺末尾の error 伝播演算子 `?`（spec 0011）は，挿入の**後**に適用する．`lhs |> g?` は `(lhs |> g)?` と等価である (MUST)．これにより `data |> validate? |> transform?` は `transform(validate(data)?)?` と書ける． | ||
| - **P5（評価順）**: 脱糖後の呼び出しの評価順（spec 0003）に従う．`lhs |> f(a, b)` は `lhs`，`a`，`b` の順に評価してから `f` を呼ぶ．左辺は常に最初に評価され，ちょうど一度だけ評価される． |
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| fn map<T, U>( | ||
| xs: Array<T>, | ||
| f: T -> U uses e | ||
| ) -> Array<U> uses e | ||
| ``` |
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WASM(WASR) ターゲットにする上で再度仕様を練り直す