Brummel
4ec8f90b19
Third tranche, completing the honesty-rule sweep across the remaining
contracts. Same conservative bar: cut unbacked-verification claims,
change/deletion history, and forward-intent; keep present-state design
rationale.
- 0003: drop "sanitiser-verified" — no TSan/sanitiser test exists in
the tree, so the claim asserts a verification that does not happen.
The data-race-freedom property (argued from the non-atomic-but-never-
shared hot path + atomic-relaxed shared counter) stays.
- 0008: the `Type::Con.name` hash paragraph ("the tightening shifted
the hashes ... The new pins ... re-asserts the pre-tightening hashes")
-> present-state: which fixtures carry which hash shape and which test
pins each.
- 0013: drop "the former codegen-side fallback (at ..., and the
now-deleted `synth_with_extras`) is retracted" (deletion history; the
present fact is that codegen does not re-resolve, per the boundary);
"A future refactor that loosens any one of the four breaks ..." ->
present-tense statement that the four are load-bearing and each pinned.
- 0017: drop "a real cost surfaced by the `bench_closure_chain`
regression at the operator-routing-eq-ord milestone" (history) and
"the symmetric extensions are mechanical when the first such workload
appears" (forward-intent); keep the present-state allocation cost, the
pin, and the Int-only-asymmetry rationale.
All 18 contracts now reviewed against the code. Ledger pins green;
honesty sweep clean.
73 lines
3.9 KiB
Markdown
73 lines
3.9 KiB
Markdown
# Prelude (built-in) classes
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## Prelude (built-in) classes
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The prelude ships the `Ordering` ADT, the `Eq` and `Ord`
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[classes](0013-typeclasses.md), primitive `Eq Int/Bool/Str/Unit` and
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`Ord Int/Bool/Str` instances, and the five polymorphic free-fn
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helpers `ne`/`lt`/`le`/`gt`/`ge`. The primitive `Eq` / `Ord`
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instance bodies carry the `(intrinsic)` marker in `examples/prelude.ail`
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(the marker is the lockstep partner to the `INTERCEPTS` registry);
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the codegen intercept `try_emit_primitive_instance_body` supplies
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their single-instruction bodies (`icmp eq i64` for `eq__Int`,
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`icmp eq i1` for `eq__Bool`, `@ail_str_eq` for `eq__Str`,
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`ret i1 1` for `eq__Unit`; a three-way `icmp` ladder constructing
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`LT`/`EQ`/`GT` for `compare__T`) and attaches `alwaysinline` so
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the call folds to the single instruction at every use site.
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The five Ord-class free helpers (`ne`/`lt`/`le`/`gt`/`ge`) have
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source-level bodies that route through `eq` / `compare` plus
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`match` over `Ordering` — written that way so the surface form is
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LLM-natural and so user-ADT instances of `Eq`/`Ord` automatically
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pick up working helpers without any per-type opt-in. At Int the
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codegen intercept short-circuits this indirection: `lt__Int`,
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`le__Int`, `gt__Int`, `ge__Int`, and `ne__Int` are intercept-
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overridden to emit `icmp slt i64` / `sle i64` / `sgt i64` /
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`sge i64` / `ne i64` directly, bypassing the `compare__Int` →
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`Ordering`-ctor → `match` path. Without this short-circuit the
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`Ordering` ctor allocates per call inside hot loops; the
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short-circuit is pinned by
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`crates/ail/tests/ord_int_intercept_ir_pin.rs`. It
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is *Int-only* by deliberate asymmetry: no current bench or
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example fixture exercises Ord-`lt`/`le`/`gt`/`ge` at Bool or
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Str at sufficient call frequency to justify the intercept-arm
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maintenance.
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Float has neither `Eq` nor `Ord` instance per [Float semantics](
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0005-float-semantics.md); a polymorphic helper invoked at Float fires
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`NoInstance` at typecheck with a Float-aware diagnostic that names
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the explicit `float_eq` / `float_lt` alternatives and
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cross-references this section. The lookup machinery that turns a
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`show x` call site into the right monomorphic instance is
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documented in [method dispatch](0016-method-dispatch.md).
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Float comparison is a separate surface: the six monomorphic prelude
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fns `float_eq` / `float_ne` / `float_lt` / `float_le` / `float_gt`
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/ `float_ge` each carry the type `(Float, Float) -> Bool` without
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a class constraint. They lower via the same intercept machinery as
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the primitive `Eq` instances (single `fcmp` instruction with the
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matching predicate `oeq` / `une` / `olt` / `ole` / `ogt` / `oge`,
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plus `alwaysinline`). They replace what would otherwise be a
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polymorphic `==` / `<` on Float — Float gets full comparability
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via explicit named fns, not via an implicit class instance.
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The prelude ships `class Show a where show : (a borrow) -> Str` and
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primitive `Show Int`, `Show Bool`, `Show Str`, `Show Float`
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instances. Float **is** included in Show (unlike Eq/Ord) — IEEE-754
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makes structural equality and total ordering semantically dubious,
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but textual representation of a Float is well-defined modulo the
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NaN-spelling caveat in [Float semantics](0005-float-semantics.md). Each
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`Show <T>` instance body is a single-application lambda invoking the
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corresponding runtime primitive (`int_to_str`, `bool_to_str`,
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`str_clone`, `float_to_str`; see [Str ABI](0011-str-abi.md) for the
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heap-Str primitives); no codegen intercept is required. The
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polymorphic helper `print : forall a. Show a => a -> () !IO` has body
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`\x -> let s = show x in do io/print_str s` (explicit let-binder for
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heap-Str RC discipline per the Str carve-out in
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[Str ABI](0011-str-abi.md)). The let-binder is
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structurally pinned by `crates/ail/tests/print_mono_body_shape.rs`.
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Routing through `print` is the path for non-`Str` primitives;
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`io/print_str` is the only built-in direct-output effect-op.
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Ratified by: `crates/ail/tests/show_no_instance_e2e.rs`.
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