erlang: spawn/1 + self/0 + is_pid (+13 tests)

plans/erlang-on-sx.md

@@ -65,7 +65,7 @@ Core mapping:
 
 ### Phase 3 — processes + mailboxes + receive (THE SHOWCASE)
 - [x] Scheduler in `runtime.sx`: runnable queue, pid counter, per-process state record — **39 runtime tests**
-- [ ] `spawn/1`, `spawn/3`, `self/0`
+- [x] `spawn/1`, `spawn/3`, `self/0` — **13 new eval tests**; `spawn/3` stubbed with "deferred to Phase 5" until modules land; `is_pid/1` + pid equality also wired
 - [ ] `!` (send), `receive ... end` with selective pattern matching
 - [ ] `receive ... after Ms -> ...` timeout clause (use SX timer primitive)
 - [ ] `exit/1`, basic process termination
@@ -99,6 +99,7 @@ Core mapping:
 
 _Newest first._
 
+- **2026-04-24 spawn/1 + self/0 green** — `erlang-eval-ast` now spins up a "main" process for every top-level evaluation and runs `er-sched-drain!` after the body, synchronously executing every spawned process front-to-back (no yield support yet — fine because receive hasn't been wired). BIFs added in `lib/erlang/runtime.sx`: `self/0` (reads `er-sched-current-pid`), `spawn/1` (creates process, stashes `:initial-fun`, returns pid), `spawn/3` (stub — Phase 5 once modules land), `is_pid/1`. Pids added to `er-equal?` (id compare) and `er-type-order` (between strings and tuples); `er-format-value` renders as `<pid:N>`. 13 new eval tests — self returns a pid, `self() =:= self()`, spawn returns a fresh distinct pid, `is_pid` positive/negative, multi-spawn io-order, child's `self()` is its own pid. Total eval 143/143; runtime 39/39; suite 296/296. Next: `!` (send) + selective `receive` using delimited continuations for mailbox suspension.
 - **2026-04-24 scheduler foundation green** — `lib/erlang/runtime.sx` + `lib/erlang/tests/runtime.sx`. Amortised-O(1) FIFO queue (`er-q-new`, `er-q-push!`, `er-q-pop!`, `er-q-peek`, `er-q-compact!` at 128-entry head drift), tagged pids `{:tag "pid" :id N}` with `er-pid?`/`er-pid-equal?`, global scheduler state in `er-scheduler` holding `:next-pid`, `:processes` (dict keyed by `p{id}`), `:runnable` queue, `:current`. Process records with `:pid`, `:mailbox` (queue), `:state`, `:continuation`, `:receive-pats`, `:trap-exit`, `:links`, `:monitors`, `:env`, `:exit-reason`. 39 tests (queue FIFO, interleave, compact; pid alloc + equality; process create/lookup/field-update; runnable dequeue order; current-pid; mailbox push; scheduler reinit). Total erlang suite 283/283. Next: `spawn/1`, `!`, `receive` wired into the evaluator.
 - **2026-04-24 core BIFs + funs green** — Phase 2 complete. Added to `lib/erlang/transpile.sx`: fun values (`{:tag "fun" :clauses :env}`), fun evaluation (closure over current env), fun application (clause arity + pattern + guard filtering, fresh env per attempt), remote-call dispatch (`lists:*`, `io:*`, `erlang:*`). BIFs: `length/1`, `hd/1`, `tl/1`, `element/2`, `tuple_size/1`, `atom_to_list/1`, `list_to_atom/1`, `lists:reverse/1`, `lists:map/2`, `lists:foldl/3`, `io:format/1-2`. `io:format` writes to a capture buffer (`er-io-buffer`, `er-io-flush!`, `er-io-buffer-content`) and returns `ok` — supports `~n`, `~p`/`~w`/`~s`, `~~`. 35 new eval tests. Total eval 130/130; erlang suite 244/244. **Phase 2 complete — Phase 3 (processes, scheduler, receive) is next.**
 - **2026-04-24 guards + is_* BIFs green** — `er-eval-call` + `er-apply-bif` in `lib/erlang/transpile.sx` wire local function calls to a BIF dispatcher. Type-test BIFs `is_integer`, `is_atom`, `is_list`, `is_tuple`, `is_number`, `is_float`, `is_boolean` all return `true`/`false` atoms. Comparison and arithmetic in guards already worked (same `er-eval-expr` path). 20 new eval tests — each BIF positive + negative, plus guard conjunction (`,`), disjunction (`;`), and arith-in-guard. Total eval 95/95; erlang suite 209/209.