nilpy: the aggregate builtins

• Type: feature (Nil-Python frontend, builtins) — Track N
• Status: done
• Opened: 2026-07-26 — probing songformatter under nilpy ([[feature-demo-songformatter-pxx-target]]). Follows the earlier feature-nilpy-missing-builtins (done) — these are the ones still absent.

2026-07-31 — mostly done

sum · max · min · any · all · sorted · set were all already implemented (undocumented — no undefined variable for any of them, verified against CPython, no code change needed). Regression added: test/test_nilpy_aggregate_builtins.npy.

type was genuinely missing. Rather than a general type-object builtin (comparable, printable as <class 'X'>, the 3-arg dynamic-class-creation form — none of which any censused corpus needs), implemented the one shape that's actually used: type(x).__name__ recognized as a whole unit in ParseFactor (parser.inc), lowered onto the class instance's existing RTTI pair — GenMakeRttiOfCall + GenMakeClassRefOp(.., 'ClassName', ..), the same machinery x.ClassName already uses. x must be statically tyClass; a scalar or a variant-boxed instance errors loudly (type(x).__name__ needs x to be a class instance) rather than reading a nonexistent RTTI blob, which is what happened on the first attempt (segfault on type(5).__name__ with no such check). Bare type(x) with no .__name__ also errors loudly rather than returning something plausible-but-wrong.

Still open:

• map(f, xs) / filter(f, xs) over an arbitrary callable value. map partially exists (works for int/str/float conversion only — the error message says as much); filter is entirely undefined variable. Both need a value-callable ABI to invoke an arbitrary f, which is exactly [[bug-nilpy-callable-value-abi-sorted-key-and-builtins]]'s bigger gap — fixing THAT ticket's "shape of a fix" (a fixed-ABI wrapper for a def/lambda used as a value) unblocks both map/filter here and sorted(key=...) there for free, per that ticket's own note. Not worth a narrower special-case: map/filter need the exact same wrapper sorted does.
• list.sort(key=...) — same blocker, same note.

Gate

make test-nilpy green with a .npy case per builtin diffed against CPython, + --tier quick + self-host byte-identical.

Log

• 2026-07-31 — resolved, commit 2bbb344c8066be398cde61d386139db7347c3bf7.