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t27o: Python dynamics -- a static subset with trace-based type inference (RightTyper, MonkeyType, Codon) #9006
Description
Part of the effects-at-the-edge epic; it feeds #8995. Research basis:
- RightTyper (arXiv 2507.16051) and MonkeyType: types observed at run time, with sampling, combined with static analysis.
- Codon: compiles Python ahead of time with bidirectional static type inference, and refuses runtime type changes.
Design:
- t27o runs the original Python under the oracle and records types at function boundaries.
- Widths are chosen from the observed integer ranges.
- A value seen with several types becomes a tagged union.
- Dynamic features (eval, monkeypatching, runtime type change, metaclasses) are refused by name.
Acceptance: types inferred for one scripts/*.py module, and a verified t27 port of at least one function.
Activity
gHashTag commentedon Oct 19, 2026
Measured 2026-10-20 (census #11168, document
docs/now/2026-10-20-python-debt.mdin PR #11176): of 331,183 distinct hand-written, non-test Python lines in the five repositories, 812 (0.25%) sit in the 105 functions that fit a typed subset today and 4,090 (1.23%) in the 454 that fit once parameter types are inferred from traces (this issue's design). No file is a whole-file candidate of 150 lines or more, and the median in-subset function has 6 lines, so a Python port deletes functions, not files, andt27c gen-pythonlowers no function today. Pure code blocked only by heap values (owned strings, dict/set, comprehensions, union/None returns, pure stdlib imports) is a further 1,293 fns / 16,577 lines (5.0%): the same wall as the Rust census.Verdict from the loop, on the threshold set before the measurement (a whole-file candidate of at least 150 lines): not met, so no Python front end is being built now. This issue stays open as the roadmap item; what would change the answer is t27 gaining the heap values named above, which is the decision recorded in the t27o report (default: not started).
docs(t27o): Python debt census -- 2,126 tracked .py files, 12,547 fun…