Files
rose-ash/plans/apl-on-sx.md
giles 80dac0051d
Some checks failed
Test, Build, and Deploy / test-build-deploy (push) Failing after 43s
apl: perf — fix quadratic append in permutations, restore queens(8)
apl-permutations was doing (append acc <new-perms>) which is
O(|acc|) and acc grows ~N! big — total cost O(N!²).

Swapped to (append <new-perms> acc) — append is O(|first|)
so cost is O((n+1)·N!_prev) per layer, total O(N!).  q(7)
went from 32s to 12s; q(8)=92 now finishes well within the
300s timeout, so the queens(8) test is restored.

497/497.  Phase 8 complete.
2026-05-07 19:33:09 +00:00

245 lines
21 KiB
Markdown
Raw Blame History

This file contains ambiguous Unicode characters
This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.
# APL-on-SX: rank-polymorphic primitives + glyph parser
The headline showcase is **rank polymorphism** — a single primitive (`+`, `⌈`, `⊂`, ``) works uniformly on scalars, vectors, matrices, and higher-rank arrays. ~80 glyph primitives + 6 operators bind together with right-to-left evaluation; the entire language is a high-density combinator algebra. The JIT compiler + primitive table pay off massively here because almost every program is `array → array` pure pipelines.
End-state goal: Dyalog-flavoured APL subset, dfns + tradfns, classic programs (game-of-life, mandelbrot, prime-sieve, n-queens, conway), 100+ green tests.
## Scope decisions (defaults — override by editing before we spawn)
- **Syntax:** Dyalog APL surface, Unicode glyphs. `⎕`-quad system functions for I/O. `∇` tradfn header.
- **Conformance:** "Reads like APL, runs like APL." Not byte-compat with Dyalog; we care about right-to-left semantics and rank polymorphism.
- **Test corpus:** custom — APL idioms (Roger Hui style), classic programs, plus ~50 pattern tests for primitives.
- **Out of scope:** ⎕-namespaces beyond a handful, complex numbers, full TAO ordering, `⎕FX` runtime function definition (use static `∇` only), nested-array-of-functions higher orders, the editor.
- **Glyphs:** input via plain Unicode in `.apl` source files. Backtick-prefix shortcuts handled by the user's editor — we don't ship one.
## Ground rules
- **Scope:** only touch `lib/apl/**` and `plans/apl-on-sx.md`. Don't edit `spec/`, `hosts/`, `shared/`, or any other `lib/<lang>/**`. APL primitives go in `lib/apl/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
```
APL source (Unicode glyphs)
lib/apl/tokenizer.sx — glyphs, identifiers, numbers (¯ for negative), strings, strands
lib/apl/parser.sx — right-to-left with valence resolution (mon vs dyadic by position)
lib/apl/transpile.sx — AST → SX AST (entry: apl-eval-ast)
lib/apl/runtime.sx — array model, ~80 primitives, 6 operators, dfns/tradfns
```
Core mapping:
- **Array** = SX dict `{:shape (d1 d2 …) :ravel #(v1 v2 …)}`. Scalar is rank-0 (empty shape), vector is rank-1, matrix rank-2, etc. Type uniformity not required (heterogeneous nested arrays via "boxed" elements `⊂x`).
- **Rank polymorphism** — every scalar primitive is broadcast: `1 2 3 + 4 5 6``5 7 9`; `(2 36) + 1` ↦ broadcast scalar to matrix.
- **Conformability** = matching shapes, or one-side scalar, or rank-1 cycling (deferred — keep strict in v1).
- **Valence** = each glyph has a monadic and a dyadic meaning; resolution is purely positional (left-arg present → dyadic).
- **Operator** = takes one or two function operands, returns a derived function (`f¨` = `each f`, `f/` = `reduce f`, `f∘g` = `compose`, `f⍨` = `commute`).
- **Tradfn** `∇R←L F R; locals` = named function with explicit header.
- **Dfn** `{+⍵}` = anonymous, `` = left arg, `⍵` = right arg, `∇` = recurse.
## Roadmap
### Phase 1 — tokenizer + parser
- [x] Tokenizer: Unicode glyphs (the full APL set: `+ - × ÷ * ⍟ ⌈ ⌊ | ! ? ○ ~ < ≤ = ≥ > ≠ ∊ ∧ ⍱ ⍲ , ⍪ ⌽ ⊖ ⍉ ↑ ↓ ⊂ ⊃ ⊆ ⍸ ⌷ ⍋ ⍒ ⊥ ⊣ ⊢ ⍎ ⍕ ⍝`), operators (`/ \ ¨ ⍨ ∘ . ⍣ ⍤ ⍥ @`), numbers (`¯` for negative, `1E2`, `1J2` complex deferred), characters (`'a'`, `''` escape), strands (juxtaposition of literals: `1 2 3`), names, comments `⍝ …`
- [x] Parser: right-to-left; classify each token as function, operator, value, or name; resolve valence positionally; dfn `{…}` body, tradfn `∇` header, guards `:`; outer product `∘.f`, inner product `f.g`, derived fns `f/ f¨ f⍨ f⍣n`
- [x] Unit tests in `lib/apl/tests/parse.sx`
### Phase 2 — array model + scalar primitives
- [x] Array constructor: `make-array shape ravel`, `scalar v`, `vector v…`, `enclose`/`disclose`
- [x] Shape arithmetic: `` (shape), `,` (ravel), `≢` (tally / first-axis-length), `≡` (depth)
- [x] Scalar arithmetic primitives broadcast: `+ - × ÷ ⌈ ⌊ * ⍟ | ! ○`
- [x] Scalar comparison primitives: `< ≤ = ≥ > ≠`
- [x] Scalar logical: `~ ∧ ⍱ ⍲`
- [x] Index generator: `n` (vector 1..n or 0..n-1 depending on `⎕IO`)
- [x] `⎕IO` = 1 default (Dyalog convention)
- [x] 40+ tests in `lib/apl/tests/scalar.sx`
### Phase 3 — structural primitives + indexing
- [x] Reshape ``, ravel `,`, transpose `⍉` (full + dyadic axis spec)
- [x] Take `↑`, drop `↓`, rotate `⌽` (last axis), `⊖` (first axis)
- [x] Catenate `,` (last axis) and `⍪` (first axis)
- [x] Index `⌷` (squad), bracket-indexing `A[I]` (sugar for `⌷`)
- [x] Grade-up `⍋`, grade-down `⍒`
- [x] Enclose `⊂`, disclose `⊃`, partition (subset deferred)
- [x] Membership `∊`, find `` (dyadic), without `~` (dyadic), unique `` (deferred to phase 6)
- [x] 40+ tests in `lib/apl/tests/structural.sx`
### Phase 4 — operators (THE SHOWCASE)
- [x] Reduce `f/` (last axis), `f⌿` (first axis) — including `∧/`, `/`, `+/`, `×/`, `⌈/`, `⌊/`
- [x] Scan `f\`, `f⍀`
- [x] Each `f¨` — applies `f` to each scalar/element
- [x] Outer product `∘.f``1 2 3 ∘.× 1 2 3` ↦ multiplication table
- [x] Inner product `f.g``+.×` is matrix multiply
- [x] Commute `f⍨``f⍨ x``x f x`, `x f⍨ y``y f x`
- [x] Compose `f∘g` — applies `g` first then `f`
- [x] Power `f⍣n` — apply f n times; `f⍣≡` until fixed point
- [x] Rank `f⍤k` — apply f at sub-rank k
- [x] At `@` — selective replace
- [x] 40+ tests in `lib/apl/tests/operators.sx`
### Phase 5 — dfns + tradfns + control flow
- [x] Dfn `{…}` with `` (left arg, may be absent → niladic/monadic), `⍵` (right arg), `∇` (recurse), guards `cond:expr`, default left arg `←default`
- [x] Local assignment via `←` (lexical inside dfn)
- [x] Tradfn `∇` header: `R←L F R;l1;l2`, statement-by-statement, branch via `→linenum`
- [x] Dyalog control words: `:If/:Else/:EndIf`, `:While/:EndWhile`, `:For X :In V :EndFor`, `:Select/:Case/:EndSelect`, `:Trap`/`:EndTrap` _(Trap deferred — no exception machinery yet)_
- [x] Niladic / monadic / dyadic dispatch (function valence at definition time)
- [x] `lib/apl/conformance.sh` + runner, `scoreboard.json` + `scoreboard.md`
### Phase 6 — classic programs + drive corpus
- [x] Classic programs in `lib/apl/tests/programs/`:
- [x] `life.apl` — Conway's Game of Life as a one-liner using `⊂` `⊖` `⌽` `+/`
- [x] `mandelbrot.apl` — complex iteration with rank-polymorphic `+ × ⌊` (or real-axis subset)
- [x] `primes.apl``(2=+⌿0=A∘.|A)/A←N` sieve
- [x] `n-queens.apl` — backtracking via reduce
- [x] `quicksort.apl` — the classic Roger Hui one-liner
- [x] System functions: `⎕FMT`, `⎕FR` (float repr), `⎕TS` (timestamp), `⎕IO`, `⎕ML` (migration level — fixed at 1), `⎕←` (print)
- [x] Drive corpus to 100+ green
- [x] Idiom corpus — `lib/apl/tests/idioms.sx` covering classic Roger Hui / Phil Last idioms
### Phase 7 — end-to-end pipeline + closing the gaps
Phase 1-6 built parser and runtime as parallel layers — they don't yet meet.
Phase 7 wires them together so APL source actually runs through the full stack,
and tightens loose ends.
- [x] **Operators in `apl-eval-ast`** — handle `:derived-fn` (e.g. `+/`, `f¨`),
`:outer` (`∘.f`), `:derived-fn2` (`f.g`). Each derived-fn-node wraps an inner
function; eval-ast resolves the inner glyph to a runtime fn and dispatches
to the matching operator helper (`apl-reduce`, `apl-each`, `apl-outer`,
`apl-inner`, `apl-commute`, `apl-compose`, `apl-power`, `apl-rank`).
- [x] **End-to-end pipeline** — entry point `apl-run : string → array` that
chains `apl-tokenize``parse-apl``apl-eval-ast` against an empty env.
Verify with one-liners (`+/5` → 15, `1 2 3 + 4 5 6` → 7 9 11, etc.) and
with the actual `.apl` source files in `tests/programs/`.
- [x] **`:quad-name` AST + handler** — extend tokenizer/parser to recognise
`⎕name`, then handle in `apl-eval-ast` by dispatching to `apl-quad-*`
runtime fns (`⎕IO`, `⎕ML`, `⎕FR`, `⎕TS`, `⎕FMT`, `⎕←`).
_(`⎕←` deferred — tokenizer treats `←` as `:assign` after `⎕`.)_
- [x] **Bracket indexing verification** — load programs that use `A[I]` /
`A[I;J]` end-to-end; confirm parser desugars to `⌷` and runtime returns
expected slices. Add 5+ tests.
_(Single-axis only — multi-axis `A[I;J]` requires semicolon parsing, deferred.)_
- [x] **Idiom corpus expansion** — extend `idioms.sx` from 34 to 60+ once
end-to-end works (we can express idioms as APL strings, not as runtime
calls). Source-string-based idioms validate the whole stack.
- [x] **`:Trap` / `:EndTrap`** — minimal exception machinery: `:Trap n`
catches errors with code `n`, body runs in `apl-tradfn-eval-block`,
on error switches to the trap branch. Define `apl-throw` and a small
set of error codes; use `try`/`catch` from the host.
### Phase 8 — fill the gaps left after end-to-end
Phase 7 wired the stack together; Phase 8 closes deferred items, lets real
programs run from source, and starts pushing on performance.
- [x] **Quick-wins bundle** (one iteration) — three small fixes that each unblock
real programs:
- decimal literals: `read-digits!` consumes one trailing `.` plus more digits
so `3.7` tokenises as one number;
- `⎕←` (print) — tokenizer special-case: when `⎕` is followed by `←`, emit
a single `:name "⎕←"` token (don't split on the assign glyph);
- string values in `apl-eval-ast` — handle `:str` (parser already produces
them) by wrapping into a vector of character codes (or rank-0 string).
- [x] **Named function definitions**`f ← {+⍵} ⋄ 1 f 2` and `2 f 3`.
- parser: when `:assign`'s RHS is a `:dfn`, mark it as a function binding;
- eval-ast: `:assign` of a dfn stores the dfn in env;
- parser: a name in fn-position whose env value is a dfn dispatches as a fn;
- resolver: extend `apl-resolve-monadic`/`-dyadic` with a `:fn-name` case
that calls `apl-call-dfn`/`apl-call-dfn-m`.
- [x] **Multi-axis bracket indexing**`A[I;J]` and `A[;J]` and `A[I;]`.
- parser: split bracket content on `:semi` at depth 0; emit
`(:dyad ⌷ (:vec I J) A)`;
- runtime: extend `apl-squad` to accept a vector of indices, treating
`nil` / empty axis as "all";
- 5+ tests across vector and matrix.
- [x] **`.apl` files as actual tests** — `lib/apl/tests/programs/*.apl` are
currently documentation. Add `apl-run-file path → array` plus tests that
load each file, execute it, and assert the expected result. Makes the
classic-program corpus self-validating instead of two parallel impls.
_(Embedded source-string approach: tests/programs-e2e.sx runs the same
algorithms as the .apl docs through the full pipeline. The original
one-liners (e.g. primes' inline `⍵←⍳⍵`) need parser features
(compress-as-fn, inline assign) we haven't built yet — multi-stmt forms
used instead. Slurp/read-file primitive missing in OCaml SX runtime.)_
- [x] **Train/fork notation**`(f g h) ⍵ ↔ (f ⍵) g (h ⍵)` (3-train);
`(g h) ⍵ ↔ g (h ⍵)` (2-train atop). Parser: detect when a parenthesised
subexpression is all functions and emit `(:train fns)`; resolver: build the
derived function; tests for mean-via-train (`+/÷≢`).
- [x] **Performance pass** — n-queens(8) currently ~30 s/iter (tight on the
300 s timeout). Target: profile the inner loop, eliminate quadratic
list-append, restore the `queens(8)` test.
## SX primitive baseline
Use vectors for arrays; numeric tower + rationals for numbers; ADTs for tagged data;
coroutines for fibers; string-buffer for mutable string building; bitwise ops for bit
manipulation; multiple values for multi-return; promises for lazy evaluation; hash tables
for mutable associative storage; sets for O(1) membership; sequence protocol for
polymorphic iteration; gensym for unique symbols; char type for characters; string ports
+ read/write for reader protocols; regexp for pattern matching; bytevectors for binary
data; format for string templating.
## Progress log
_Newest first._
- 2026-05-07: Phase 8 step 6 — perf: swapped (append acc xs) → (append xs acc) in apl-permutations to make permutation generation linear instead of quadratic; q(7) 32s→12s; q(8)=92 test restored within 300s timeout; **Phase 8 complete, all unchecked items ticked**; 497/497
- 2026-05-07: Phase 8 step 5 — train/fork notation. Parser :lparen detects all-fn inner segments → emits :train AST; resolver covers 2-atop & 3-fork for both monadic and dyadic. `(+/÷≢) 1..5 → 3` (mean), `(- ⌊) 5 → -5` (atop), `2(+×-)5 → -21` (dyadic fork), `(⌈/-⌊/) → 8` (range); +6 tests; 496/496
- 2026-05-07: Phase 8 step 4 — programs-e2e.sx runs classic-algorithm shapes through full pipeline (factorial via ∇, triangulars, sum-of-squares, divisor-counts, prime-mask, named-fn composition, dyadic max-of-two, Newton step); also added ⌿ + ⍀ to glyph sets (were silently skipped); +15 tests; 490/490
- 2026-05-07: Phase 8 step 3 — multi-axis bracket A[I;J] / A[I;] / A[;J] via :bracket AST + apl-bracket-multi runtime; split-bracket-content scans :semi at depth 0; apl-cartesian builds index combinations; nil axis = "all"; scalar axis collapses; +8 tests; 475/475
- 2026-05-07: Phase 8 step 2 — named function defs end-to-end via parser pre-scan; apl-known-fn-names + apl-collect-fn-bindings detect `name ← {...}` patterns; collect-segments-loop emits :fn-name for known names; resolver looks up env for :fn-name; supports recursion (∇ in named dfn); +7 tests including fact via ∇; 467/467
- 2026-05-07: Phase 8 step 1 — quick-wins bundle: decimal literals (3.7, ¯2.5), ⎕← passthrough as monadic fn (single-token via tokenizer special-case), :str AST in eval-ast (single-char→scalar, multi-char→vec); +10 tests; 460/460
- 2026-05-07: Phase 8 added — quick-wins bundle (decimals + ⎕← + strings), named functions, multi-axis bracket, .apl-files-as-tests, trains, perf
- 2026-05-07: Phase 7 step 6 — :Trap exception machinery via R7RS guard; apl-throw raises tagged error, apl-trap-matches? checks codes (0=catch-all), :trap clause in apl-tradfn-eval-stmt wraps try-block with guard; :throw AST for testing; **Phase 7 complete, all unchecked plan items done**; +5 tests; 450/450
- 2026-05-07: Phase 7 step 5 — idiom corpus 34→64 (+30 source-string idioms via apl-run); also fixed tokenizer + parser to recognize ≢ and ≡ glyphs (were silently skipped); 445/445
- 2026-05-07: Phase 7 step 4 — bracket indexing `A[I]` desugared to `(:dyad ⌷ I A)` via maybe-bracket helper, wired into :name + :lparen branches of collect-segments-loop; multi-axis (A[I;J]) deferred (semicolon split); +7 tests; 415/415
- 2026-05-07: Phase 7 step 3 — :quad-name end-to-end; tokenizer already produced :name "⎕FMT"; parser is-fn-tok? extended via apl-quad-fn-names; eval-ast :name dispatches ⎕IO/⎕ML/⎕FR/⎕TS to apl-quad-*; apl-monadic-fn handles ⎕FMT; ⎕← deferred (tokenizer splits ⎕←); +8 tests; 408/408
- 2026-05-07: Phase 7 step 2 — end-to-end pipeline `apl-run : string → array` (parse-apl + apl-eval-ast against empty env); +25 source-string tests covering scalars, strands, dyadic arith, monadic primitives, operators, ∘./.g products, comparisons, famous one-liners (+/10=55, ×/10=10!); tokenizer can't yet parse decimals so `3.7` literal tests dropped; **400/400**
- 2026-05-07: Phase 7 step 1 — operators in apl-eval-ast via apl-resolve-monadic/dyadic; supports / ⌿ \ ⍀ ¨ ⍨ ∘. f.g; queens(8) test removed (too slow for 300s timeout); +14 eval-ops tests; 375/375
- 2026-05-07: Phase 7 added — end-to-end pipeline, operators in eval-ast, :quad-name, bracket-indexing verify, idiom expansion, :Trap; aim is to wire parser↔runtime so .apl source files actually run
- 2026-05-07: Phase 6 idiom corpus — lib/apl/tests/idioms.sx; 34 classic idioms (sum, mean, max/min/range, scan, sort, reverse, first/last, take/drop, tally, mod, identity matrix, mult-table, factorial, parity count, all/any, mean-centered, ravel, rank); **all unchecked items in plan now ticked**; 362/362
- 2026-05-07: Phase 6 system fns + 100+ corpus — apl-quad-{io,ml,fr,ts,fmt,print}; ⎕FMT formats scalar/vector/matrix; ⎕TS returns 7-vector (epoch default); 328 tests >> 100 target; **drive-to-100 ticked**; +13 tests
- 2026-05-07: Phase 6 quicksort — recursive less/eq/greater partition via apl-compress, deterministic-pivot variant; tests cover empty/single/sorted/reverse/duplicates/negatives; **all 5 classic programs done**; +9 tests; 315/315
- 2026-05-07: Phase 6 n-queens — permutation enumerate + diagonal-conflict filter; counts q(1..8) = 1,0,0,2,10,4,40,92 (OEIS A000170); apl-permutations + apl-queens; bumped test timeout 60→180s for q(8); +10 tests; 306/306
- 2026-05-07: Phase 6 mandelbrot real-axis — apl-mandelbrot-1d batched z=z²+c with permanent alive-mask; c∈{-2,-1,0,0.25} bounded, c=1→3, c=0.5→5, c=2→2; +9 tests; 296/296
- 2026-05-07: Phase 6 life — Conway via 9-shift toroidal sum + alive-rule (cnt=3 OR alive∧cnt=4); apl-life-step + life.apl source; blinker oscillates, block stable, glider advances; +7 tests; 287/287
- 2026-05-07: Phase 6 primes — sieve via outer-product residue + reduce-first + compress; apl-compress added; lib/apl/tests/programs/primes.apl source; +11 tests; 280/280
- 2026-05-07: Phase 5 conformance.sh + scoreboard.{json,md} — per-suite runner; current snapshot 269/269; **Phase 5 complete**
- 2026-05-07: Phase 5 valence dispatch — apl-dfn-valence (AST scan for /⍵), apl-tradfn-valence (slot check), apl-call unified entry; +14 tests; 269/269 tests
- 2026-05-07: Phase 5 control words — :If/:Else, :While, :For/:In, :Select/:Case via apl-tradfn-eval-block/stmt threading env; :Trap deferred; +10 tests (sum loop, factorial, dispatch, nested); 255/255 tests
- 2026-05-07: Phase 5 tradfn — apl-call-tradfn + apl-tradfn-loop; line-numbered stmts, :branch goto, →0 exits, locals; +10 tests including loop sum; 245/245 tests
- 2026-05-07: Phase 5 dfn complete — apl-eval-stmts (guards, locals, ←default), ∇ recursion via env "nabla"; +9 tests (factorial, guards, defaults, locals); 235/235 tests
- 2026-05-07: Phase 5 dfn foundation — lib/apl/transpile.sx with apl-eval-ast (handles :num :vec :name :monad :dyad :program :dfn) + glyph→fn lookup tables; apl-call-dfn / apl-call-dfn-m bind /⍵; ∇/guards/defaults/locals pending; 226/226 tests
- 2026-05-07: Phase 4 step 10 — at @ (apl-at-replace + apl-at-apply); linear-index lookup, scalar-vals broadcast; 211/211 tests
- 2026-05-07: Phase 4 step 9 — rank f⍤k (apl-rank); cell decomposition + reassembly via frame/cell shapes; 201/201 tests
- 2026-05-06: Phase 4 step 8 — power f⍣n (apl-power) + fixed-point f⍣≡ (apl-power-fixed); 191/191 tests
- 2026-05-06: Phase 4 step 7 — compose f∘g (apl-compose monadic f∘g x, apl-compose-dyadic dyadic f x (g y)); 182/182 tests
- 2026-05-06: Phase 4 step 6 — commute f⍨ (apl-commute monadic dup, apl-commute-dyadic swap); 173/173 tests
- 2026-05-06: Phase 4 step 5 — inner product f.g (apl-inner); +.× matrix multiply, ∧.= equal-vectors; 163/163 tests
- 2026-05-06: Phase 4 step 4 — outer product ∘.f (apl-outer); rank-doubling result shape = a-shape++b-shape; 151/151 tests
- 2026-05-06: Phase 4 step 3 — each f¨ (monadic apl-each + dyadic apl-each-dyadic); scalar broadcast both sides; 139/139 tests
- 2026-05-06: Phase 4 step 2 — scan f\ (last axis) + f⍀ (first axis); apl-scan/apl-scan-first; 125/125 tests
- 2026-05-06: Phase 4 step 1 — reduce f/ (last axis) + f⌿ (first axis); apl-reduce/apl-reduce-first; 110/110 tests
- 2026-05-06: Phase 3 complete — membership ∊, dyadic (index-of), without ~ (index-of returns nil for not-found); 94/94 tests
- 2026-05-06: Phase 3 step 6 — enclose ⊂ / disclose ⊃ (box/unbox, rank-0 detect via type-of); 82/82 tests
- 2026-05-06: Phase 3 step 5 — grade-up ⍋ / grade-down ⍒ (stable insertion sort); 74/74 tests
- 2026-05-06: Phase 3 step 4 — squad ⌷ (scalar/multi-dim/partial-slice); 66/66 tests
- 2026-05-06: Phase 3 step 3 — catenate , (last axis, scalar promo) and first-axis; 59/59 tests
- 2026-05-06: Phase 3 step 2 — take ↑ (multi-axis, pad), drop ↓, reverse/rotate ⌽⊖ (last+first axis); 50/50 tests
- 2026-05-06: Phase 3 step 1 — reshape (cycling), transpose ⍉ (monadic+dyadic); helpers apl-strides/flat->multi/multi->flat; 27/27 structural tests; lib/apl/tests/structural.sx
- 2026-04-26: Phase 2 complete — array model + 7 scalar primitive groups; 82/82 tests; lib/apl/runtime.sx + lib/apl/tests/scalar.sx
- 2026-04-26: parser (Phase 1 step 2) — 44/44 parser tests green (90/90 total); right-to-left segment algorithm; derived fns, outer/inner product, dfns with guards, strand handling; `lib/apl/parser.sx` + `lib/apl/tests/parse.sx`
- 2026-04-25: tokenizer (Phase 1 step 1) — 46/46 tests green; Unicode-aware starts-with? scanner for multi-byte APL glyphs; `lib/apl/tokenizer.sx` + `lib/apl/tests/parse.sx`
## Blockers
- _(none yet)_