feature: PXX Basic — own free-form BASIC dialect (real demo target, not an esoteric probe)

• Type: feature (Track A — compiler/blexer.inc/bparser.inc, lib/ RTL bits as needed)
• Status: done
• Owner: —
• Opened: 2026-07-05 (user idea: "we're totally free to do as we see fit, there are no standards, just intentions — wild demo")

What this is, and how it's different from the esoteric-probe category

Not part of [[feature-esoteric-frontend-probes]] — that category is explicitly capped at "skeleton only, stop at trivial, success = bug found or clean pass, never chase usability." PXX Basic is the opposite intent: an actual, finished, fun, demo-worthy dialect that's ours to shape however we want, no spec to match, no BASIC standard body to satisfy. Same spirit as Nil-Python (PXX's own take on a Python-like surface, not CPython-compatible) — BASIC gets the same treatment.

What already exists (confirmed by reading the tree, not assumed)

compiler/blexer.inc (249 lines) + compiler/bparser.inc (378 lines) already implement a real, already-blended dialect:

• Classic line-numbered style (10 PRINT "hi", GOTO/GOSUB/RETURN) and modern numberless style (FOR i = 1 TO 10 STEP 2 / NEXT i, WHILE/WEND) accepted in the same program, freely mixed. Already a deliberately non-standard choice — no real BASIC dialect does this.
• USES my_pas_lib / USES my_c_lib — BASIC code calling real Pascal and C functions directly, per test/test_basic_comprehensive.bas (already written, already exercises this).
• test/test_basic_lexer.bas, test/test_basic_comprehensive.bas, test/my_pas_lib.pas, test/my_c_lib.c — test fixtures already in the tree.

Docs already mention it exists: docs/targets/cross-languages.md lists .bas as "BASIC, experimental" in the frontend-by-suffix table — but nothing beyond that one line, and no progress ticket existed for it until this one.

What's blocking it right now

[[bug-basic-goto-gosub-halts-program]] — GOTO/GOSUB are lexed straight to tkHalt (stub/placeholder token reuse, looks unfinished rather than intentional), so any program using classic line-numbered control flow silently halts instead of running. This has to land first — it's not a "make it nicer" gap, it's "half the dialect doesn't execute."

Scope ideas (not committed, brainstorm-tier — refine when picked up)

• Fix the GOTO/GOSUB/RETURN bug first (see above).
• Decide how far to lean into "free-form, no standard" as a feature rather than an accident: e.g. keep the deliberate classic+modern blend, maybe add PXX-specific flourishes (a REPL mode reusing the examples/lisp REPL pattern? direct access to any PXX RTL/PCL unit via USES, not just hand-written demo shims?).
• A demo program written to show off the mixed-style + cross-language-import angle specifically — that combination (line numbers and modern loops and calling real Pascal/C) is the actual novelty worth showing, not "yet another BASIC."
• Consider whether this belongs under examples/ (a demo, Track B) once the frontend itself (Track A) is solid, mirroring how the C/Nil-Python frontends split from their demo programs.

Acceptance (loose — this is a demo/fun target, not a strict spec)

test/test_basic_comprehensive.bas runs end-to-end and prints everything it claims to (currently silently truncates after ~1 line, see the blocking bug). Beyond that: "is it a fun demo" is the real bar, not a formal conformance suite — no BASIC standard to satisfy, by design.

Log

• 2026-07-05 — filed from a user brainstorm; found the frontend already exists (untracked) and already has personality (mixed dialect + cross-language import), but is blocked by a real GOTO/GOSUB bug filed separately as [[bug-basic-goto-gosub-halts-program]].

• 2026-07-19 (backlog sweep) RESOLVED. Sole blocker (GOTO/GOSUB) fixed 19a18872; test_basic_goto_gosub + comprehensive wired into make test. REPL/flourish ideas were explicitly brainstorm-tier — re-file if ever wanted.

• 2026-07-19 — resolved, commit 19a18872.