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NilPy: a function is a VALUE — bind it to a name, store it, call it back

Three spellings, all ordinary Python, all rejected today (measured against compiler/pascal26 at 8ae0f99f):

def add(a, b):
    return a + b

f = add            # pascal26: error: unexpected token   near:  add >>> f
g = lambda x: x+1  # pascal26: error: unexpected token   (statement-level lambda)
hs = [add]
print(hs[0](3, 4)) # calling a function VALUE out of a container

PyMakeFuncValue already BUILDS a function value (a def handed to a Callable[...] parameter marshals correctly since [[bug-nilpy-callable-return-abi-mismatch]]), and pyboundfn_new / pyboundfn_bind_var lift a captures-only nested def into a real proc. What is missing is the other two halves:

  1. the bare def NAME as an expression in an assignment / a literal — today the parser only accepts a def name in CALL position, so f = add does not parse at all;
  2. the CALL side on a value — f(), hs[0](5), d["k"](x) — invoking whatever the name/element holds rather than a statically resolved proc.

lambda as a statement-level assignment (g = lambda ...) is the same gap seen from the lambda side: a lambda in ARGUMENT position works (sorted(xs, key=lambda p: p[1]), bind(..., lambda e: ...)), because that path builds the value where the parser expects an expression.

Why it matters here

songformatter's convertrawtext.py and the render backends pass functions around (an injected canvas backend is a set of callables), and every Python program that builds a dispatch table writes handlers = {"x": on_x}. It is also the shape [[feature-nilpy-lambda-compiled-closure]] needs: once a lambda lifts to a real proc, the value it produces has to be storable and callable.

Resolved 2026-07-29 (commits 170cde9e2, 4cb96a3b6, cab5a5179)

All three spellings verified against CPython, plus a call through a dict and a list element. NOTE: this ticket carried the SAME slug as an older, narrower feature-nilpy-function-values (already in done/); renamed on resolution so the two files stop colliding in the board.

Gate

make test-nilpy with a case covering all three spellings, CPython-diffed, plus a call through a dict/list element.