Brummel
b151990028
Architect drift review at raw-buf milestone close (after 55d76ae closed
#43) surfaced three items; this commit clears them. All three lockstep-
invariant pairs were confirmed intact and the effective-name keying was
confirmed consistent across the desugar→lift boundary (lift_letrecs reads
the desugared tree's effective names too).
1. [high] Honesty fix. `fresh_binder`'s doc-comment (and 55d76ae's body)
claimed "authored names cannot contain `$` — the lexer reserves it".
False: the lexer (ailang-surface) reserves only `.`, not `$`. The
`$`-for-synthetic convention is not enforced. So collision-freedom
rests solely on the `used` + in-scope-`scope` probe, which does not
see an authored `<base>$<n>` that is out of scope at mint time but
later binds under the same `(def, name)` key — the very collision
class this fix closes. Latent (no fixture uses a `$` binder), but the
stated rationale was wrong. Doc-comment now describes the probe
honestly and names the gap + its two possible closures (enforce the
reservation, or seed `used` with every authored binder name in the
def). The enforce-or-retract decision is the next-direction follow-up.
2. [medium] design/models/0003-pipeline.md — "desugar currently only
flattens nested constructor patterns" no longer matches the code
(it now also alpha-renames shadowing binders). Corrected to current
state (honesty-rule).
3. [low] design/contracts/0008-memory-model.md — the three drop gates
all key on `(def_name, binder_name)` consume_count, silently relying
on per-fn binder-name injectivity, which the ledger never stated.
Added that invariant as an explicit precondition of the gates, with
the desugar guarantee and its ratifying tests.
No code-logic change; doc-comment + ledger only.
83 lines
4.6 KiB
Markdown
83 lines
4.6 KiB
Markdown
# Pipeline and CLI
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## Pipeline
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```
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.ail.json ─┐
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├─ load + validate schema
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├─ resolve names + assign hashes
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├─ desugar (AST → AST)
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├─ typecheck (HM, effect rows; mode-strict per the memory model)
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├─ lift_letrecs (post-typecheck AST → AST)
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├─ lower to MIR (SSA-like, named SSA values)
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├─ emit LLVM IR (.ll)
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└─ clang -O2 *.ll -o binary
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--alloc=rc → emits inc/dec (@ailang_rc_inc / _dec; canonical, default)
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--alloc=bump → links bump-floor (@bump_malloc; raw-alloc bench-floor)
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```
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Two allocator backends share the same MIR. `--alloc=rc` is the
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canonical backend committed to in the
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[memory model](../contracts/0008-memory-model.md) and the CLI default;
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the typechecker enforces `(own)` / `(borrow)` modes, codegen emits
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`ailang_rc_inc` / `_dec` calls at the points dictated by linearity,
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and `Term::Clone` / `Term::ReuseAs` materialise into actual rc-bumps
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and in-place rewrites respectively. `--alloc=bump` selects the
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raw-alloc bench-floor (`runtime/bump.c`, no free, leak-only) and is
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used by `bench/run.sh` to measure RC overhead against the
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structurally cheapest allocator — it is not a production target.
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The **desugar** pass
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([`ailang-core::desugar::desugar_module`](../../crates/ailang-core/src/desugar.rs))
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runs before typecheck and codegen in every entry point of
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`ailang-check` and `ailang-codegen`. It is a pure AST → AST rewriter —
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it flattens nested constructor patterns and alpha-renames any binder
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whose name shadows an enclosing binding to a fresh `<name>$<n>` (so the
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uniqueness side-table's `(def_name, binder_name)` key is injective per
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fn), and is the chosen home for any future surface-smoothing rewrites
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that should not bloat the core AST or the backends. **Critical invariant:** `CheckedModule.symbols`
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in the `check` entry point continues to hash from the *original*
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on-disk module, not the desugared one, so `ail diff` and `ail manifest`
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report identities that match the canonical JSON the user is editing.
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The **lift_letrecs** pass (`ailang-check::lift_letrecs`)
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runs **after** typecheck and **before** codegen, but only on the
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`build` / `run` paths — the `check` subcommand stops at typecheck
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and never sees a lifted module. It eliminates every `Term::LetRec`
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that the desugar pass left in place (the case where at least one
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capture is `Term::Let`-bound, so its type is only knowable after
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inference). The output is a module with synthetic `<hint>$lr_N`
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top-level fns appended, ready for codegen. Synthetic FnDefs added
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by this pass do **not** appear in `CheckedModule.symbols` — same
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invariant as the desugar-pass lifts.
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## CLI
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```
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ail check <module.ail.json> — loads, validates, typechecks
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ail manifest <module.ail.json> — table: name :: type !effects [hash]
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ail describe <module> <name> — detail of a definition (form-A body)
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ail render <module.ail.json> — JSON-AST → form-A text (exact inverse of `parse`)
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ail parse <module.ail> — form-A text → canonical JSON-AST
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ail prose <module.ail.json> — JSON-AST → form-B (lossy human prose, no parser)
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ail merge-prose <m.ail.json> <m.prose.txt>
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— compose the LLM-mediator prompt for the prose round-trip
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ail deps <module.ail.json> — list cross-module references
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ail diff <a.ail.json> <b.ail.json> — content-addressed def-level diff
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ail workspace <entry.ail.json> — list all modules transitively reachable from entry
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(`--json` for machine output;
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`manifest --workspace` and `diff --workspace`
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extend single-module subcommands to workspaces)
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ail builtins — list built-in fns and effect ops
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ail emit-ir <module> [--emit=staticlib] — writes .ll (staticlib: a main-free kernel's IR, no @main)
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ail build <module> [--emit=staticlib] — full pipeline → binary (staticlib: lib<entry>.a + libailang_rt.a)
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ail run <module> — build + execute (tempdir), passthrough exit code
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```
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The text projections the CLI moves between are documented in
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[authoring surface](../contracts/0001-authoring-surface.md) (Form-A,
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round-trippable) and [prose projection](0006-prose-projection.md)
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(Form-B, lossy, no parser); `ail build --emit=staticlib` produces
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the layout fixed in [embedding ABI](../contracts/0003-embedding-abi.md)
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plus [frozen value layout](../contracts/0006-frozen-value-layout.md).
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