closure2_py2.py

#!/usr/bin/env python

def outer():
    times_called = 0
    def inner():
        print "called", times_called, "times"
    return inner

f = outer()
f()

closure4_py2.py

#!/usr/bin/env python                                                                         

ret = lambda y: y
bind = lambda x, f=ret: f(x)

def foo():
    data = 0
    def bar():
        bar.get = lambda: data
        bar.set = lambda n: bind(
            [None for data in [n]], lambda _:
            ret(data))
        return bar
    return bar


a = foo()
assert a().set(5) == 5
assert a().get() == 5

closure5_py2.py

def Foo(xs, acc = {}):
    if not xs:
        return acc['a0'] + acc['a1'] if acc else 0
    if not acc:
        acc['a0'], acc['a1'] = xs[0], 0
    else:
        acc['a0'], acc['a1'] = xs[0], acc['a0'] + acc['a1']
    return Foo(xs[1:], acc)

print Foo([1,2,3,4])
print Foo([1,2,3])     # wrong


def Foo(xs0):
    def Bar(xs, acc = {}):
        if not xs:
            return acc['a0'] + acc['a1'] if acc else 0
        if not acc:
            acc['a0'], acc['a1'] = xs[0], 0
        else:
            acc['a0'], acc['a1'] = xs[0], acc['a0'] + acc['a1']
        return Bar(xs[1:], acc)
    return Bar(xs0)

print Foo([1,2,3,4])
print Foo([1,2,3])

closure_py2.py

#!/usr/bin/env python

def outer():
    times_called = 0
    def inner():
        times_called += 1
        print "called", times_called, "times"
    return inner

f = outer()
f()

closure_py3.py

#!/usr/bin/env python3                                                                        

def outer():
    times_called = 0
    def inner():
        nonlocal times_called
        times_called += 1
        print("called", times_called, "times")
    return inner

f = outer()
f()