Brummel
19dc42f5ca
The first formal-links milestone shipped clause-5 + 8 links across the
existing file layout. Browsing surfaced that file-only granularity is
only as precise as the file boundaries — three files mixed two or
three navigation targets under one address, so the 8 links could not
multiply without ambiguity. This commit fixes the substrate, then
applies the sweep the original milestone deferred.
Splits (each extracts an already-self-contained section into its own
file so links land on the topic, not the parent doc's TOC):
contracts/typeclasses.md
→ +contracts/prelude-classes.md (Eq/Ord/Show ships, polymorphic `print`)
→ +contracts/method-dispatch.md (5-step dispatch rule, candidate index)
contracts/memory-model.md
→ +contracts/language-constraints.md (the 4 binding constraints
making RC sound without a
cycle collector)
models/authoring-surface.md
→ +models/prose-projection.md (Form-B / `ail prose` / merge-prose)
Each new file enters design/INDEX.md as its own row (three contracts
share show_no_instance_e2e.rs / uniqueness.rs as ratifying tests;
prose-projection is a model). Two pre-existing links rebind to the
new topic-files (memory-model.md → method-dispatch.md;
float-semantics.md → prelude-classes.md).
Link sweep: 8 → 88 formal Markdown links over 23 files. Every file
in design/contracts/ + design/models/ now has at least one outgoing
link; the tree is fully connected. Links are file-relative
`[label](path)` per the established convention, fenced code blocks
are skipped (a `](` inside ```jsonc``` is literal text), the durable
tier (design/ + crates/ + runtime/) is enforced by clause-5.
Tests:
- design_index_pin.rs (5/5 clauses): clean-cut, INDEX resolution,
ratifying-test resolution, no decision-record prose in contracts/,
body links durable + resolving.
- docs_honesty_pin.rs (5/5): one assertion rebinds from typeclasses.md
to prelude-classes.md (where the gated sentence now lives);
design_corpus widens to include the 4 new files so the Wunschdenken
/ doc-archaeology sweeps continue to cover everything that used to
live in the parents.
No spec/plan/journal for this batch — interactive collaboration after
the milestone closed; the user gated the splits explicitly before the
sweep.
73 lines
3.3 KiB
Markdown
73 lines
3.3 KiB
Markdown
# Embedding ABI
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## Embedding ABI
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`ail build --emit=staticlib` compiles a module to a relocatable
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`lib<entry>.a` (program objects only) plus a separate
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`libailang_rt.a` (the RC runtime: `rc.c` + `str.c`), with **no**
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`@main` trampoline and **no** `MissingEntryMain` requirement — a
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kernel module is a library.
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Each `fn` carrying `(export "<sym>")` (schema: `FnDef.export`) is
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emitted as an externally-visible C entrypoint `@<sym>` forwarding to
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the internal `@ail_<module>_<fn>`. The symbol is author-chosen and
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decoupled from the `ail_<module>_<def>` mangling so a module/fn
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rename does not move the C symbol.
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The set that can cross the boundary is exactly: `Int` (lowered
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`i64`), `Float` (lowered `double`), or a single-constructor record
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whose every field is one of those (crossing as a bare `ptr` to the
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box layout below); the fn's effect set must be empty. There is no
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general value-marshalling layer — the host hand-constructs and
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hand-reads that box layout directly, so the enumerated set *is* the
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whole contract, narrow by construction, not a subset of a wider
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embedding ABI. Because the box layout is the host's contract
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surface with no accessor indirection, it is a **one-way commitment
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frozen as of M3**: a compiler change MUST NOT move the box offsets
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below for an exported type, nor invert the host-free rule.
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These are enforced at `ail check` (`export-non-scalar-signature`,
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`export-has-effects`) — an effectful or non-scalar export *fails to
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typecheck*. Every exported entrypoint takes a mandatory leading `ailang_ctx_t*`
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(M2): a per-thread embedding context created by `ailang_ctx_new()`
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and released by `ailang_ctx_free()`, owned by the calling thread for
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its lifetime. The host links one `ailang_ctx_t` per OS worker thread
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and the runtime accounts RC alloc/free into it: the per-allocation
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hot path (the per-ctx counters and the per-object refcount header)
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is non-atomic by design and never shared — a box never crosses a
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thread (`Ctx: !Send`) and each `ailang_ctx_t` is
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single-thread-per-ctx. The one datum a multi-threaded host shares
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is the global RC-stats fallback counter (used when no ctx is
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bound); it is atomic-relaxed so the swarm's leak accounting is
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exact. The swarm artefact is data-race-free, sanitiser-verified.
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The staticlib swarm artefact is **RC-only**:
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`ail build --emit=staticlib` rejects `--alloc=gc`/`--alloc=bump`
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(the shared Boehm collector is not swarm-safe). The value/record
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layout is **frozen as of M3** (see [Frozen value layout](frozen-value-layout.md)); the
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ctx-threaded C signature is the M2 shape.
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Export parameters are written **bare**: a scalar type carries no
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`own`/`borrow` mode (a single-constructor record export parameter,
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by contrast, carries `own`/`borrow` — see [memory model](memory-model.md)
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for the full ownership contract; the
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frozen value layout below specifies how that contract lands at the C ABI). The
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canonical M1 export shape:
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```
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(fn step
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(export "backtest_step")
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(type
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(fn-type
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(params (con Int) (con Int))
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(ret (con Int))))
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(params state sample)
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(body
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(app + state (app * sample sample))))
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```
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`ail emit-ir <module> --emit=staticlib` prints this kernel's LLVM
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IR (the external `@<sym>` forwarders, no `@main`) instead of the
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executable-path `main`-required rejection — the Decision-5
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IR-readability affordance for a `main`-free kernel.
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Ratified by: `crates/ailang-codegen/tests/embed_record_layout_pin.rs`.
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