Brummel
768189abce
Exploratory model that converges the direction sparked by the
typed-MIR fieldtest Implicit-return leak (spec 0061). It is not
current state and not an approved milestone — the surface still
defaults ParamMode::Implicit; the file fixes a future shape before
committing it to specs.
The converged shape:
- Ownership is authored, never defaulted. Implicit is removed from
the authorable surface; every parameter and return carries
own/borrow. A default cannot be half-removed, so totality is the
only coherent stopping point.
- Value types take trivial-own; borrow over a value type is an
error. The surface stays uniform so the author needs no knowledge
of which types are heap.
- No mode-polymorphism. A type-variable position is never a hole
under fixed modes — it takes a concrete own/borrow. Mode variables
would only remove duplication, and the reuse-across-modes need is
confined to point-free combinators (cut by the language identity)
and the consume-vs-preserve container duality (better expressed as
two named functions). Structurally, AILang iterates via tail-app,
not passed-function combinators, so the higher-order own/borrow
clash does not arise. ParamMode stays binary {Own, Borrow}.
Left open: cutover shape, verification sequencing, glossary naming.
The one irreversible consequence — a corpus-wide module-hash reset
once Implicit stops eliding the mode fields from canonical JSON — is
named for deliberate sign-off.