plans: Phase 8 — quick-wins, named fns, multi-axis brackets, .apl-as-tests, trains, perf

plans/apl-on-sx.md

@@ -135,6 +135,43 @@ and tightens loose ends.
   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.
+
+- [ ] **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).
+- [ ] **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`.
+- [ ] **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.
+- [ ] **`.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.
+- [ ] **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 (`+/÷≢`).
+- [ ] **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;
@@ -149,6 +186,7 @@ data; format for string templating.
 
 _Newest first._
 
+- 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