Measured 2026-09-19

def size(t):
    return t
print(size.__name__)   # NilPy: compile error `undefined variable (size)`
f = size
print(f.__name__)      # NilPy: AttributeError

Where it shows in a real program

argparse builds invalid <type name> value: 'x' from type.__name__. tsp/view/main.py passes type=_size, a def. CPython prints argument --size: invalid _size value: 'wide'. lib/rtl/mimic_argparse.py falls back to repr, so NilPy prints invalid <function at 0x5ae82b> value. That case (view --size wide) was left OUT of test/test_nilpy_argparse_tsp_surface.cases for this reason; put it back when this ticket lands.

Two halves, one representation

• The static spelling size.__name__: the frontend knows the def, so it can fold to a string literal.
• The dynamic spelling needs the name in the boxed callable. It is the same representation that repr() reads, so fixing it fixes both.