The canonical sx block-body lambda is `(params) { stmts }` (and
`(params) -> Ret { stmts }`); the arrow form `=>` is for EXPRESSION bodies
(`(params) => expr`). The arrow-block hybrid `(params) => { .. }` was being
used in 33 files — convert all of them by dropping the `=>`. The two forms are
exactly equivalent (verified: identical IR and identical runtime values — the
block tail is the value with or without a `-> Ret`), so this is a pure source
cleanup: no `.ir` churn, and the only snapshot change is 0923's diagnostic
COLUMN (a negative narrowing test whose error span shifted by the removed `=> `).
Arrow EXPRESSION bodies (`=> expr`, `=> .{..}`, `=> [..]`) and `=>` inside
comments/strings were left untouched. Migrated across examples/concurrency,
examples/{closures,ffi-objc,generics,optionals,types}, issues/, and the stdlib
(io.sx, sched.sx). Suite 855/0.
Converge the Io unification (PLAN-IO-UNIFY Phase 5). The bespoke fiber-task layer
in sched.sx — Task / TaskState / TaskErr / go / wait / cancel(Task), plus
Scheduler.task_allocs and its deinit bookkeeping (~130 lines) — is removed. There
is now ONE async stack: context.io.async / await / cancel / race / sleep over the
Io protocol, with the Scheduler as the fiber Io's engine + driver (spawn /
yield_now / suspend_self / wake / run / block_on_fd remain as the raw primitives;
race stays in sched.sx because it needs meta.sx's make_enum/make_variant).
Migrated the four go/wait users to context.io:
- 1813 — interleave + cancel (sequence 1 2 3 42 100 -99)
- 1817 — m1 end-to-end (completion in deadline order, sum 123)
- 1819 — double-AWAIT loud-abort via the Future one-awaiter guard
- 1820 — deinit: dropped the go/task_allocs tasks; now exercises timers/io_waiters/
kq cleanup (freed=2, live=3 = the documented per-spawn closure-env residual)
Updated readme.md (the user-facing async section documents context.io.async /
await / race / sleep) and the stale sched.go/sched.Task comments in io.sx.
Suite 854/0; no .ir churn (Task removal touched no snapshotted IR); migrated
examples byte-identical on aarch64-macOS + aarch64-linux. PLAN-IO-UNIFY Phases 0-5
all complete — the two parallel async stacks are now one, behind context.io.
Scheduler.deinit closes the bounded leaks B1 documented: it reaps any leftover
ready fibers, frees every heap Task from go (now tracked via a task_allocs
field), frees the timers/io_waiters/task_allocs List backings, and closes the
lazily-opened kqueue fd. Terminal + idempotent; the per-spawn/go closure env
remains unfreeable (language limitation). Locked by
examples/concurrency/1820-concurrency-fiber-scheduler-deinit.sx, which exercises
every freed resource under a tracking GPA (freed by deinit: 5, kq reset to -1).
Also converts plain-struct '= ---'+field-assign init to '.{ ... }' literal init
where '---' carries no meaning: Scheduler.init, Dock.make, and the fiber
examples 1811/1813/1814/1816 (partial literals zero-fill the index-filled array
fields). Unions, '---'-feature tests, the 0154 regression, documented
generic-pack gaps, and loop/conditional inits are intentionally left on '---'.
library/modules/std/sched.sx: a generic Fiber + Scheduler over the
proven naked swap_context on guarded mmap stacks --
init/spawn/yield_now/suspend_self/wake/run (B1.5a), then Task($R) +
go/wait/cancel, a truly-suspending nullary-thunk async layer (B1.4a).
go(work) runs a thunk as a real fiber; wait() parks the caller until it
completes. Self-contained in sched.sx (io.sx importing it would
duplicate the _fib_tramp global asm).
Hardened per adversarial review: wake guarded on .suspended (FIFO
corruption), suspend_self/yield_now guard a null current, loud
mmap/mprotect/OOM/deadlock bails, cancel skips not-yet-run work.
Closure-env + heap-Task leaks documented (bounded, default-GPA-invisible).
Examples: 1811 (round-robin), 1812 (suspend/wake + spurious-wake guard),
1813 (async interleave + await-suspend + cancel). Also files issue 0155
(scalar-pointer index panics codegen -- non-blocking, found in review).
