def test_chain():
rl = chain(posdec, posdec)
assert rl(5) == 3
assert rl(1) == 0
def bottom_up(rule, fns=basic_fns):
""" Apply a rule down a tree running it on the bottom nodes first """
return chain(lambda expr: sall(bottom_up(rule, fns), fns)(expr), rule)
def top_down(rule, fns=basic_fns):
""" Apply a rule down a tree running it on the top nodes first """
return chain(rule, lambda expr: sall(top_down(rule, fns), fns)(expr))
def test_chain():
rl = chain(posdec, posdec)
assert rl(5) == 3
assert rl(1) == 0
