Cursed decorators

cursed.py

# Chapter 1: immediate evaluation with optional composition

@lambda f: not f()
def true() -> bool:
  return False
  
assert true == True # ???


# Chapter 2: single line composition

from functools import partial

@partial(partial, lambda f, *a, **k: not f(*a, **k))
def inv(x: bool) -> bool:
  return x

assert inv(true) == (not true) # ???


# Chapter 3: [something useful maybe](https://stackoverflow.com/a/24047214)

from functools import reduce

@partial(partial, lambda f, *fs: reduce(f, fs))
def compose(f, g):
  def composed(*a, **k):
    return f(g(*a, **k))
  return composed

@partial(compose, lambda x: not x, lambda x: not x)
def ident(x: bool) -> bool:
  return x

assert ident(true) == true


# Epilogue: recursive comprehension?

@partial(compose, list)
def postorder(tree: list[int], n: int = 0):
  if n >= len(tree):
    return
  yield from postorder(tree, 2 * n + 1)
  yield from postorder(tree, 2 * n + 2)
  yield n

Well done

That's horribly beautiful, or beautifully horrible... not sure which one...