smalltalk: plan + briefing + sx-loops 8th slot

Showcase: blocks with non-local return on captured method-return
continuation. ANSI-ish Smalltalk-80 subset, SUnit + Pharo Kernel-Tests
slice, 7 phases. Worktree: /root/rose-ash-loops/smalltalk on
branch loops/smalltalk.
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2026-04-25 00:05:31 +00:00
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# smalltalk-on-sx loop agent (single agent, queue-driven)
Role: iterates `plans/smalltalk-on-sx.md` forever. Message-passing OO + **blocks with non-local return** on delimited continuations. Non-local return is the headline showcase — every other Smalltalk reinvents it on the host stack; on SX it falls out of the captured method-return continuation.
```
description: smalltalk-on-sx queue loop
subagent_type: general-purpose
run_in_background: true
isolation: worktree
```
## Prompt
You are the sole background agent working `/root/rose-ash/plans/smalltalk-on-sx.md`. Isolated worktree, forever, one commit per feature. Never push.
## Restart baseline — check before iterating
1. Read `plans/smalltalk-on-sx.md` — roadmap + Progress log.
2. `ls lib/smalltalk/` — pick up from the most advanced file.
3. If `lib/smalltalk/tests/*.sx` exist, run them. Green before new work.
4. If `lib/smalltalk/scoreboard.md` exists, that's your baseline.
## The queue
Phase order per `plans/smalltalk-on-sx.md`:
- **Phase 1** — tokenizer + parser (chunk format, identifiers, keywords `foo:`, binary selectors, `#sym`, `#(…)`, `$c`, blocks `[:a | …]`, cascades, message precedence)
- **Phase 2** — object model + sequential eval (class table bootstrap, message dispatch, `super`, `doesNotUnderstand:`, instance variables)
- **Phase 3** — **THE SHOWCASE**: blocks with non-local return via captured method-return continuation. `whileTrue:` / `ifTrue:ifFalse:` as block sends. 5 classic programs (eight-queens, quicksort, mandelbrot, life, fibonacci) green.
- **Phase 4** — reflection + MOP: `perform:`, `respondsTo:`, runtime method addition, `becomeForward:`, `Exception` / `on:do:` / `ensure:` on top of `handler-bind`/`raise`
- **Phase 5** — collections + numeric tower + streams
- **Phase 6** — port SUnit, vendor Pharo Kernel-Tests slice, drive corpus to 200+
- **Phase 7** — speed (optional): inline caching, block intrinsification
Within a phase, pick the checkbox that unlocks the most tests per effort.
Every iteration: implement → test → commit → tick `[ ]` → Progress log → next.
## Ground rules (hard)
- **Scope:** only `lib/smalltalk/**` and `plans/smalltalk-on-sx.md`. Do **not** edit `spec/`, `hosts/`, `shared/`, other `lib/<lang>/` dirs, `lib/stdlib.sx`, or `lib/` root. Smalltalk primitives go in `lib/smalltalk/runtime.sx`.
- **NEVER call `sx_build`.** 600s watchdog. If sx_server binary broken → Blockers entry, stop.
- **Shared-file issues** → plan's Blockers with minimal repro.
- **Delimited continuations** are in `lib/callcc.sx` + `spec/evaluator.sx` Step 5. `sx_summarise` spec/evaluator.sx first — 2300+ lines.
- **SX files:** `sx-tree` MCP tools ONLY. `sx_validate` after edits.
- **Worktree:** commit locally. Never push. Never touch `main`.
- **Commit granularity:** one feature per commit.
- **Plan file:** update Progress log + tick boxes every commit.
## Smalltalk-specific gotchas
- **Method invocation captures `^k`** — the return continuation. Bind it as the block's escape token. `^expr` from inside any nested block invokes that captured `^k`. Escape past method return raises `BlockContext>>cannotReturn:`.
- **Blocks are lambdas + escape token**, not bare lambdas. `value`/`value:`/… invoke the lambda; `^` invokes the escape.
- **`ifTrue:` / `ifFalse:` / `whileTrue:` are ordinary block sends** — no special form. The runtime intrinsifies them in the JIT path (Tier 1 of bytecode expansion already covers this pattern).
- **Cascade** `r m1; m2; m3` desugars to `(let ((tmp r)) (st-send tmp 'm1 ()) (st-send tmp 'm2 ()) (st-send tmp 'm3 ()))`. Result is the cascade's last send (or first, depending on parser variant — pick one and document).
- **`super` send** looks up starting from the *defining* class's superclass, not the receiver class. Stash the defining class on the method record.
- **Selectors are interned symbols.** Use SX symbols.
- **Receiver dispatch:** tagged ints / floats / strings / symbols / `nil` / `true` / `false` aren't boxed. Their classes (`SmallInteger`, `Float`, `String`, `Symbol`, `UndefinedObject`, `True`, `False`) are looked up by SX type-of, not by an `:class` field.
- **Method precedence:** unary > binary > keyword. `3 + 4 factorial` is `3 + (4 factorial)`. `a foo: b bar` is `a foo: (b bar)` (keyword absorbs trailing unary).
- **Image / fileIn / become: between sessions** = out of scope. One-way `becomeForward:` only.
- **Test corpus:** ~200 hand-written + a slice of Pharo Kernel-Tests. Place programs in `lib/smalltalk/tests/programs/`.
## General gotchas (all loops)
- SX `do` = R7RS iteration. Use `begin` for multi-expr sequences.
- `cond`/`when`/`let` clauses evaluate only the last expr.
- `type-of` on user fn returns `"lambda"`.
- Shell heredoc `||` gets eaten — escape or use `case`.
## Style
- No comments in `.sx` unless non-obvious.
- No new planning docs — update `plans/smalltalk-on-sx.md` inline.
- Short, factual commit messages (`smalltalk: tokenizer + 56 tests`).
- One feature per iteration. Commit. Log. Next.
Go. Read the plan; find first `[ ]`; implement.

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# Smalltalk-on-SX: blocks with non-local return on delimited continuations
The headline showcase is **blocks** — Smalltalk's closures with non-local return (`^expr` aborts the enclosing *method*, not the block). Every other Smalltalk on top of a host VM (RSqueak on PyPy, GemStone on C, Maxine on Java) reinvents non-local return on whatever stack discipline the host gives them. On SX it's a one-liner: a block holds a captured continuation; `^` just invokes it. Message-passing OO falls out cheaply on top of the existing component / dispatch machinery.
End-state goal: ANSI-ish Smalltalk-80 subset, SUnit working, ~200 hand-written tests + a vendored slice of the Pharo kernel tests, classic corpus (eight queens, quicksort, mandelbrot, Conway's Life).
## Scope decisions (defaults — override by editing before we spawn)
- **Syntax:** Pharo / Squeak chunk format (`!` separators, `Object subclass: #Foo …`). No fileIn/fileOut images — text source only.
- **Conformance:** ANSI X3J20 *as a target*, not bug-for-bug Squeak. "Reads like Smalltalk, runs like Smalltalk."
- **Test corpus:** SUnit ported to SX-Smalltalk + custom programs + a curated slice of Pharo `Kernel-Tests` / `Collections-Tests`.
- **Image:** out of scope. Source-only. No `become:` between sessions, no snapshotting.
- **Reflection:** `class`, `respondsTo:`, `perform:`, `doesNotUnderstand:` in. `become:` (object-identity swap) **in** — it's a good CEK exercise. Method modification at runtime in.
- **GUI / Morphic / threads:** out entirely.
## Ground rules
- **Scope:** only touch `lib/smalltalk/**` and `plans/smalltalk-on-sx.md`. Don't edit `spec/`, `hosts/`, `shared/`, or any other `lib/<lang>/**`. Smalltalk primitives go in `lib/smalltalk/runtime.sx`.
- **SX files:** use `sx-tree` MCP tools only.
- **Commits:** one feature per commit. Keep `## Progress log` updated and tick roadmap boxes.
## Architecture sketch
```
Smalltalk source
lib/smalltalk/tokenizer.sx — selectors, keywords, literals, $c, #sym, #(…), $'…'
lib/smalltalk/parser.sx — AST: classes, methods, blocks, cascades, sends
lib/smalltalk/transpile.sx — AST → SX AST (entry: smalltalk-eval-ast)
lib/smalltalk/runtime.sx — class table, MOP, dispatch, primitives
```
Core mapping:
- **Class** = SX dict `{:name :superclass :ivars :methods :class-methods :metaclass}`. Class table is a flat dict keyed by class name.
- **Object** = SX dict `{:class :ivars}``ivars` keyed by symbol. Tagged ints / floats / strings / symbols are not boxed; their class is looked up by SX type.
- **Method** = SX lambda closing over a `self` binding + temps. Body wrapped in a delimited continuation so `^` can escape.
- **Message send** = `(st-send receiver selector args)` — does class-table lookup, walks superclass chain, falls back to `doesNotUnderstand:` with a `Message` object.
- **Block** `[:x | … ^v … ]` = lambda + captured `^k` (the method-return continuation). Invoking `^` calls `k`; outer block invocation past method return raises `BlockContext>>cannotReturn:`.
- **Cascade** `r m1; m2; m3` = `(let ((tmp r)) (st-send tmp 'm1 ()) (st-send tmp 'm2 ()) (st-send tmp 'm3 ()))`.
- **`ifTrue:ifFalse:` / `whileTrue:`** = ordinary block sends; the runtime intrinsifies them in the JIT path so they compile to native branches (Tier 1 of bytecode expansion already covers this pattern).
- **`become:`** = swap two object identities everywhere — in SX this is a heap walk, but we restrict to `oneWayBecome:` (cheap: rewrite class field) by default.
## Roadmap
### Phase 1 — tokenizer + parser
- [ ] Tokenizer: identifiers, keywords (`foo:`), binary selectors (`+`, `==`, `,`, `->`, `~=` etc.), numbers (radix `16r1F`, scaled `1.5s2`), strings `'…''…'`, characters `$c`, symbols `#foo` `#'foo bar'` `#+`, byte arrays `#[1 2 3]`, literal arrays `#(1 #foo 'x')`, comments `"…"`
- [ ] Parser: chunk format (`! !` separators), class definitions (`Object subclass: #X instanceVariableNames: '…' classVariableNames: '…' …`), method definitions (`extend: #Foo with: 'bar ^self'`), pragmas `<primitive: 1>`, blocks `[:a :b | | t1 t2 | …]`, cascades, message precedence (unary > binary > keyword)
- [ ] Unit tests in `lib/smalltalk/tests/parse.sx`
### Phase 2 — object model + sequential eval
- [ ] Class table + bootstrap: `Object`, `Behavior`, `Class`, `Metaclass`, `UndefinedObject`, `Boolean`/`True`/`False`, `Number`/`Integer`/`Float`, `String`, `Symbol`, `Array`, `Block`
- [ ] `smalltalk-eval-ast`: literals, variable reference, assignment, message send, cascade, sequence, return
- [ ] Method lookup: walk class → superclass; cache hit-class on `(class, selector)`
- [ ] `doesNotUnderstand:` fallback constructing `Message` object
- [ ] `super` send (lookup starts at superclass of *defining* class, not receiver class)
- [ ] 30+ tests in `lib/smalltalk/tests/eval.sx`
### Phase 3 — blocks + non-local return (THE SHOWCASE)
- [ ] Method invocation captures a `^k` (the return continuation) and binds it as the block's escape
- [ ] `^expr` from inside a block invokes that captured `^k`
- [ ] `BlockContext>>value`, `value:`, `value:value:`, …, `valueWithArguments:`
- [ ] `whileTrue:` / `whileTrue` / `whileFalse:` / `whileFalse` as ordinary block sends — runtime intrinsifies the loop in the bytecode JIT
- [ ] `ifTrue:` / `ifFalse:` / `ifTrue:ifFalse:` as block sends, similarly intrinsified
- [ ] Escape past returned-from method raises `BlockContext>>cannotReturn:`
- [ ] Classic programs in `lib/smalltalk/tests/programs/`:
- [ ] `eight-queens.st`
- [ ] `quicksort.st`
- [ ] `mandelbrot.st`
- [ ] `life.st` (Conway's Life, glider gun)
- [ ] `fibonacci.st` (recursive + memoised)
- [ ] `lib/smalltalk/conformance.sh` + runner, `scoreboard.json` + `scoreboard.md`
### Phase 4 — reflection + MOP
- [ ] `Object>>class`, `class>>name`, `class>>superclass`, `class>>methodDict`, `class>>selectors`
- [ ] `Object>>perform:` / `perform:with:` / `perform:withArguments:`
- [ ] `Object>>respondsTo:`, `Object>>isKindOf:`, `Object>>isMemberOf:`
- [ ] `Behavior>>compile:` — runtime method addition
- [ ] `Object>>becomeForward:` (one-way become; rewrites the class field of `aReceiver`)
- [ ] Exceptions: `Exception`, `Error`, `signal`, `signal:`, `on:do:`, `ensure:`, `ifCurtailed:` — built on top of SX `handler-bind`/`raise`
### Phase 5 — collections + numeric tower
- [ ] `SequenceableCollection`/`OrderedCollection`/`Array`/`String`/`Symbol`
- [ ] `HashedCollection`/`Set`/`Dictionary`/`IdentityDictionary`
- [ ] `Stream` hierarchy: `ReadStream`/`WriteStream`/`ReadWriteStream`
- [ ] `Number` tower: `SmallInteger`/`LargePositiveInteger`/`Float`/`Fraction`
- [ ] `String>>format:`, `printOn:` for everything
### Phase 6 — SUnit + corpus to 200+
- [ ] Port SUnit (TestCase, TestSuite, TestResult) — written in SX-Smalltalk, runs in itself
- [ ] Vendor a slice of Pharo `Kernel-Tests` and `Collections-Tests`
- [ ] Drive the scoreboard up: aim for 200+ green tests
- [ ] Stretch: ANSI Smalltalk validator subset
### Phase 7 — speed (optional)
- [ ] Method-dictionary inline caching (already in CEK as a primitive; just wire selector cache)
- [ ] Block intrinsification beyond `whileTrue:` / `ifTrue:`
- [ ] Compare against GNU Smalltalk on the corpus
## Progress log
_Newest first. Agent appends on every commit._
- _(none yet)_
## Blockers
_Shared-file issues that need someone else to fix. Minimal repro only._
- _(none yet)_

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@@ -30,7 +30,7 @@ fi
if [ "$CLEAN" = "1" ]; then
cd "$(dirname "$0")/.."
for lang in lua prolog forth erlang haskell js hs; do
for lang in lua prolog forth erlang haskell js hs smalltalk; do
wt="$WORKTREE_BASE/$lang"
if [ -d "$wt" ]; then
git worktree remove --force "$wt" 2>/dev/null || rm -rf "$wt"
@@ -39,5 +39,5 @@ if [ "$CLEAN" = "1" ]; then
done
git worktree prune
echo "Worktree branches (loops/<lang>) are preserved. Delete manually if desired:"
echo " git branch -D loops/lua loops/prolog loops/forth loops/erlang loops/haskell loops/js loops/hs"
echo " git branch -D loops/lua loops/prolog loops/forth loops/erlang loops/haskell loops/js loops/hs loops/smalltalk"
fi

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@@ -1,5 +1,5 @@
#!/usr/bin/env bash
# Spawn 7 claude sessions in tmux, one per language loop.
# Spawn 8 claude sessions in tmux, one per language loop.
# Each runs in its own git worktree rooted at /root/rose-ash-loops/<lang>,
# on branch loops/<lang>. No two loops share a working tree, so there's
# zero risk of file collisions between languages.
@@ -9,7 +9,7 @@
#
# After the script prints done:
# tmux a -t sx-loops
# Ctrl-B + <window-number> to switch (0=lua ... 6=hs)
# Ctrl-B + <window-number> to switch (0=lua ... 7=smalltalk)
# Ctrl-B + d to detach (loops keep running, SSH-safe)
#
# Stop: ./scripts/sx-loops-down.sh
@@ -38,8 +38,9 @@ declare -A BRIEFING=(
[haskell]=haskell-loop.md
[js]=loop.md
[hs]=hs-loop.md
[smalltalk]=smalltalk-loop.md
)
ORDER=(lua prolog forth erlang haskell js hs)
ORDER=(lua prolog forth erlang haskell js hs smalltalk)
mkdir -p "$WORKTREE_BASE"
@@ -66,7 +67,7 @@ for lang in "${ORDER[@]:1}"; do
tmux new-window -t "$SESSION" -n "$lang" -c "$WORKTREE_BASE/$lang"
done
echo "Starting 7 claude sessions..."
echo "Starting 8 claude sessions..."
for lang in "${ORDER[@]}"; do
tmux send-keys -t "$SESSION:$lang" "claude" C-m
done
@@ -89,10 +90,10 @@ for lang in "${ORDER[@]}"; do
done
echo ""
echo "Done. 7 loops started in tmux session '$SESSION', each in its own worktree."
echo "Done. 8 loops started in tmux session '$SESSION', each in its own worktree."
echo ""
echo " Attach: tmux a -t $SESSION"
echo " Switch: Ctrl-B <0..6> (0=lua 1=prolog 2=forth 3=erlang 4=haskell 5=js 6=hs)"
echo " Switch: Ctrl-B <0..7> (0=lua 1=prolog 2=forth 3=erlang 4=haskell 5=js 6=hs 7=smalltalk)"
echo " List: Ctrl-B w"
echo " Detach: Ctrl-B d"
echo " Stop: ./scripts/sx-loops-down.sh"