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What works on nanopython

Auto-generated from golden-programs/ by tools/gen_compatibility.py. Don't edit by hand; re-run make compatibility after changing the bucket assignments.

This document answers "does my Python program work in nanopython today?" across 823 curated real-world programs sourced from MicroPython's tests, CPython's tests, PEP examples, and project-specific demos. The bucketing rationale is in ADR 008.

Headline

  • 579 / 756 programs (76.6%) run on both native AND wasm.
  • 584 / 756 (77.2%) run on native (incl. native-only).
  • The remaining 172 programs are bucketed by what they need; see below.

How to read this

Each bucket below names what's missing: needs-stdlib means we don't yet ship the needed module, needs-async means async/await work is deferred, etc. Programs in works/ are tested every build by make check (native, byte-exact) and make wasm-check (wasm, baseline-subtracted).

The buckets

works/: 579 programs

Runs correctly on both native nanopython AND wasm. These programs work right now; they pass on make check and make wasm-check and have been verified to match MicroPython or CPython output.

By source corpus: prescrypt-micropython=418, prescrypt-tryalgo=79, prescrypt-internal=53, p2w-internal=29

Top requirements: async×9, grammar.walrus×6, stdlib.bisect×2, fs.open×1, stdlib.heapq×1, stdlib.collections.Counter×1

Programs (first 30):

0prelim, __init__, anagrams, andor, annotate_var, arithm, arithm_expr_eval, arithm_expr_target, array_add, array_construct, array_construct2, array_construct_endian, array_micropython, assert_statements, assign, assign1, assign_expr, assign_expr_scope, async, async_await, async_def, async_for, async_syntaxerror, async_with, async_with_break, async_with_return, bellman_ford, bfs, biconnected_components, binary_search

…and 549 more; see golden-programs/works/.

works-native-only/: 5 programs

Runs on native nanopython but not wasm. The blocker is usually the vendor nlr_jump longjmp wall: eval(), exec(), compile() from user code can't unwind on wasmtime. See ADR 009 Lane A1.

By source corpus: prescrypt-micropython=4, p2w-internal=1

Programs (first 5):

int1, int_bytes, large_integers, memoryview_intbig, special_methods

needs-stdlib/: 123 programs

Needs one or more stdlib modules we don't yet ship. The header comment on each program names the specific module. The frozen-tiny stdlib expansion (ADR 003 + ADR 009 Lane A3a) is closing this gap.

By source corpus: prescrypt-micropython=88, prescrypt-tryalgo=17, p2w-internal=10, prescrypt-internal=8

Top requirements: stdlib.tryalgo-internal×14, stdlib.random×4, stdlib.heapq×1, stdlib.collections.namedtuple×1

Programs (first 30):

array1, array_intbig, attrtuple1, bipartite_vertex_cover, builtin_abs_intbig, builtin_bin_intbig, builtin_compile, builtin_divmod_intbig, builtin_hash_intbig, builtin_help, builtin_hex_intbig, builtin_oct_intbig, builtin_override, builtin_pow3, builtin_pow3_intbig, builtin_round_int, builtin_round_intbig, builtins_introspection, builtins_iteration_simple, builtins_iteration_tools, builtins_numeric_extra, builtins_numeric_simple, bytearray_append, bytearray_byte_operations, bytearray_intbig, bytearray_slice_assign, bytes_construct, bytes_construct_intbig, bytes_encoding, class_bases

…and 93 more; see golden-programs/needs-stdlib/.

needs-grammar/: 2 programs

Uses syntax we don't yet parse. Headline gaps: walrus :=, match statements, some PEP-617 cases. Real grammar work needed.

By source corpus: prescrypt-micropython=1, prescrypt-internal=1

Top requirements: grammar.walrus×1, grammar.match×1

Programs (first 2):

assign_expr_syntaxerror, match_statements

needs-async/: 3 programs

Uses async/await/async for/async with. Currently deferred (ADR 002 Path B).

By source corpus: prescrypt-micropython=3

Top requirements: async×3

Programs (first 3):

async_await2, async_for2, async_with2

needs-fs/: 8 programs

Uses open() / file I/O. No HAL on native nano; wasm uses WASI which the demos haven't wired up. Bucketed separately so the feature can land independently.

By source corpus: prescrypt-tryalgo=7, prescrypt-micropython=1

Top requirements: fs.sys.stdin×4, fs.open×4, stdlib.random×2, stdlib.tryalgo-internal×2, stdlib.collections.defaultdict×1

Programs (first 8):

freivalds, horn_sat, interval_cover, kruskal, our_std, range_minimum_query, shortest_cycle, sys_path

needs-mpz/: 0 programs

Hits the LONGLONG ceiling (2**63 on wasm32). Needs MICROPY_LONGINT_IMPL_MPZ. Has a size cost we're tracking (ADR 009 Lane A3c).

No programs in this bucket.

disagreement/: 36 programs

MicroPython and CPython produce different output for these programs. Bucketed for human review rather than a silent bucket assignment.

By source corpus: prescrypt-micropython=36

Programs (first 30):

attrtuple2, builtin_range_binop, builtin_str_hex, bytes_compare3, bytes_escape_unicode, class_inplace_op2, errno1, exception_chain, fun_code, fun_code_colines, fun_code_full, fun_code_micropython, gen_yield_from_throw_multi_arg, generator_pend_throw, generator_throw_multi_arg, is_isnot_literal, memoryview_itemsize, memoryview_slice_size, module2, namedtuple_asdict, op_error_literal, python34, slice_op, string_escape_invalid, string_fstring_invalid, subclass_native_call, subclass_native_exc_new, sys_getsizeof, sys_tracebacklimit, try_finally_break

…and 6 more; see golden-programs/disagreement/.