The script is in tools/ rather than thrown away, because two lanes are
writing Flan in the old spelling right now and their files need the same
pass at merge.
It works on forms, not on text: a keyword becomes a dot only where it sits
in a field-label position inside a brace, so an enum member in value
position, a map key inside an EDN string and a type-position {K V} are all
left alone. :keys keeps its colon -- it names no field.
The debug-info arm and the structural printer are each a separate path from
everything the suite was exercising: `outputs ~dev:true` goes through the cells,
not through DWARF, and no program printed a Vec or an allocator. That is
NEXT.md's landed item 2 exactly — field_addr took only Types.Named, so the
printer's Option arm had never run and would have died on the first (Option T)
pointed at it. Both arms work; both are now reached, and the DWARF row asserts
the composite's size as well as its name, because an element count that
disagreed with `lay` would print plausible values for the wrong fields.
Printing a Vec did not work: `println` checked its argument as an ordinary read,
so it moved, and every printing of a Vec would have been its last. Printing is a
borrow — the walk goes over the value and keeps nothing.
And `vec-new` with an explicitly named null allocator no longer substitutes the
heap for it. Adopting the context for a *zeroed* Vec is the documented rule;
quietly substituting for an allocator the program named is the same "released
the region / never made one" collapse free-all already traps for, except silent
and found later as a leak. The no-allocator-named case never arrives as null —
the checker passes flan_context_allocator(), which always answers one.
Two element types, one runtime, and the element type appears nowhere below
the call site: size_of and align_of are produced where the concrete type is
known, which without generics is simply the concrete call site. That is
Odin's arrangement and it is what spec-memory.md specifies. `at` and `len`
were already the names for a fixed array and a slice, so a Vec extends them
rather than adding a parallel pair — the asymmetry `nth` was removed for —
and the value form and the place form go through one helper so they cannot
drift apart.
StorageExhausted lands with step 2 rather than after it, because the
signatures depend on it: `push` and `reserve` are Unit, `clone` is the
container, and nothing grows a Result. It is built out of nodes that already
existed — a while, a restart-case and an error — so the backend learned
nothing about allocation. The restart is established at the failing
allocation, which spec-memory.md names as the exception to "restarts go at
the resync point, once", and the element a push was given is bound to a slot
before the loop so a retry re-attempts the allocation and not the expression.
Move-only is a dead set on the checker context, and it is flow-sensitive at
an `if`: both arms start from the same set and the union survives the join,
so `(if c (free v) (free v))` is legal and a one-armed free still kills the
binding. The case a dead set cannot answer is a move inside a loop — merged
once at the end of the body it counts one move, not two — so that is a rule,
refused with its reason.
Four decisions the spec did not settle:
The Vec header is six words in every build, not four in release. A layout
that changes with a build flag can disagree across the reload boundary
silently: a redefinition module is built by llc and ld against a host built
separately, and nothing makes the two agree on a struct size. The 32-byte
release layout is deferred on that.
A zeroed Vec has a null allocator, and the first operation needing storage
adopts the context allocator. Odin's behaviour. The alternative was refusing a
Vec-typed struct field until drop lands; shipping the null was a null deref on
the first push.
A Vec's length and index are i32, like every other length here. Widening
indices is one change across all the containers, not a Vec question.
`let` has no type annotation, so a local Vec has nowhere to say what it holds
and the element type is written at the call: `(vec-new i32)`. This is not the
explicit instantiation syntax the generics section rules out — nothing here is
generic and the name resolves as an ordinary type. Where the context says, it
may be left out.
The allocator grew a budget: a ceiling on live bytes, 0 for none. The retry
restart is only answerable by a handler that can make the *same* request
succeed, and for a fixed backing store the handler that works is the one that
raises the ceiling — releasing the region a container lives in invalidates
the container, which is what the epoch check catches. The spec's "grows the
arena and then invokes retry" needed something to grow.
The generation word is bumped on every reallocation and read by nothing. The
stale-slice trap it is for needs a slice that can carry the Vec's identity,
and a slice is ptr+len. Said plainly rather than implied by the word's
presence.
