writeonce/docs/plan/oop-vm
shoney.arickathil 993a540d7a fix: nullable scalars need their own nil word; EQS accepts nil
Found by running the compiled log-watcher, not by reading code: the supervisor
rejected every cron line ("malformed schedule: * * * * *") because a `*` field
expands to 0 and `?Int`'s nil was also 0, so `a == nil` was true for a real
value. Both log-watcher subcommands now behave: `watch` alerts on a live file,
`run` reports SCHEDULE /var/log/backup.log: * * * * *. corpus 71/0, woc 565/0,
wovm gates green.

- a nullable SCALAR (?Int/?Bool/?Timestamp/?Id) spells nil as WO_NIL_SCALAR
  (-2^62), not the zero word. Heap-shaped optionals keep 0 — a null pointer is
  unambiguous. The value is -2^62 and NOT INT64_MIN on purpose: the compiler's
  integers are OCaml's 63-bit natives, so INT64_MIN is not expressible there
  (and `min_int * 2` silently wraps to 0 — the first attempt did exactly that)
- the class table marks such fields (WOB_FIELD_NIL_SCALAR in field_class), so
  the runtime writes the right absence where it produces absence itself:
  json.decode leaving a key absent or seeing `null`, and parse_int on
  unparseable input (so parse_int("0") is now distinguishable from a failure).
  json.encode renders a nil scalar as JSON null
- emit.ml: `nil` takes its word from its destination (annotation, field,
  return type); a comparison against `nil` emits the literal with the other
  operand's type, so ?scalar compares against the sentinel and ?heap against 0
- vm.c: EQS accepts a nil operand — two `?Text` values compare with it, and the
  answer is "both absent is equal, one absent is not". Trapping there made
  `a != b` on optionals unusable (it was trapping BOUNDS "null text" in the
  supervisor's rescan). A non-nil operand must still be a real Text
- docs: both normative docs now state the heap-vs-scalar nil split and the EQS
  rule; the stale duplicate vm_unwind comment is gone

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
2026-08-14 17:28:50 +02:00
..
00-wob-format.md fix: nullable scalars need their own nil word; EQS accepts nil 2026-08-14 17:28:50 +02:00
01-error-catalog.md feat(compiler): iteration 5 Tasks 1-4 — modules, language surface, switch, typedef records + enum variants 2026-08-12 14:40:07 +02:00
02-corpus.md feat(compiler): iteration 5 Tasks 1-4 — modules, language surface, switch, typedef records + enum variants 2026-08-12 14:40:07 +02:00
08-builtin-surface.md fix: nullable scalars need their own nil word; EQS accepts nil 2026-08-14 17:28:50 +02:00
README.md feat: milestone 1 complete — .wob emitter, conformance corpus, single binary; GC redesign specced 2026-08-11 19:31:26 +02:00

docs/plan/oop-vm/ — OOP + systems track contracts

The normative contract documents both stacks cite. Landed by their named plan tasks:

doc contract plan
00-wob-format.md .wob bytecode format (compiler↔VM) 1
01-error-catalog.md every WO-E### code 2, grows 3/8
02-corpus.md how to add conformance fixtures 3
03-shard-actor.md shard ownership, mailboxes, send-as-move 4
04-db-binding.md row format, WAL records, query subset 5
05-http-service.md route section, trap→HTTP table, JSON subset 6
06-ui-live.md delta frames, subscribe protocol, wo:live 7
07-systems-stdlib.md per-function nil-vs-trap contracts 9
08-builtin-surface.md builtin source names, container/call/entry rules the emitter enforces 3

Specs and plans: docs/superpowers/{specs,plans}/. Repo map: docs/08-project-structure.md.