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Brummel 19dc42f5ca design/ ledger: dense cross-linking via three topical splits + 88-link sweep

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.

2026-05-20 00:24:08 +02:00

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Method dispatch

The class-method resolution rule that pairs with the typeclasses contract; the Show/Eq/Ord instances the rule dispatches against live in prelude classes.

Post-mq.3, dispatch is two-mode:

Polymorphic call sites (inside a fn body with forall + constraint set): the constraint names the class via the qualified Constraint.class field (canonical-form per mq.1). Synth's residual carries the class name directly; constraint-discharge at fn-body-end matches against the workspace registry by (class, type_hash) key.

Monomorphic call sites: synth consults the workspace-flat Env.method_to_candidate_classes: BTreeMap<MethodName, BTreeSet<QualifiedClassName>> index, then runs the 5-step dispatch rule:

Parse the Term::Var.name for an optional class qualifier (last-dot-segment is the method name; everything before is the qualified class).
If method_to_candidate_classes has no entry for the method name, fall through to the existing Var-arm branches (free fn lookup, dot-qualified cross-module).
Qualifier present: filter candidates to the named class. Empty result fires UnknownClass. Singleton survivor proceeds.
Qualifier empty (bare-method form): singleton candidate proceeds directly; multiple candidates yield a multi-candidate residual for discharge-time refinement.
At discharge, refinement runs: concrete type_ filters candidates via the workspace registry; rigid-var type_ filters via the active fn's declared constraints (env.active_declared_constraints). Single survivor discharges; multiple survivors fire AmbiguousMethodResolution (concrete) or MissingConstraint (rigid-var); zero survivors fire NoInstance (concrete) or MissingConstraint (rigid-var).

The method_to_candidate_classes index is the load-bearing data structure for this routing — its construction in build_check_env inverts the per-module class_methods maps (themselves tuple-keyed by (qualified-class, method) post-mq.3) to a workspace-flat method-name-to-class-set map.

Class-fn collisions resolve at the call site, not at workspace load time: the fn lookup precedence (locals → caller-module-fn → imported-fn) runs ahead of the class-method branch. When both sides have a match, the fn wins and a class-method-shadowed-by-fn warning surfaces the shadow.

Ratified by: crates/ail/tests/show_no_instance_e2e.rs.

2.4 KiB Raw Blame History

Method dispatch

Method dispatch

2.4 KiB

Raw Blame History