python_face_runnable.pyaff

# face: python
# SPDX-License-Identifier: MPL-2.0
#
# End-to-end proof (2026-07-07) that a *face-authored* program compiles
# through the Python face → canonical → typecheck → wasm and RUNS with the
# right answer. This is the README's headline claim ("faces are the product")
# exercised for real, not just parsed.
#
# Recursion, not a loop: the Python face currently drops the trailing `;` on
# the last statement of a while/for body (issue #683), so face-authored loops
# don't yet compile. Recursion's tail line is a value expression, which the
# face handles correctly — so this proves the face→wasm path without waiting
# on #683. (Variable names also avoid the `total` soft-keyword collision,
# issue #682.)

def fac(n: Int) -> Int:
    if n == 0:
        1
    else:
        n * fac(n - 1)

def sum_to(n: Int) -> Int:
    if n == 0:
        0
    else:
        n + sum_to(n - 1)

def main() -> Int:
    # fac(5)=120, sum_to(100)=5050  ->  120 + 5050 = 5170
    fac(5) + sum_to(100)