>>> car = 
    
    lambda
    
     lst: lst[0]
>>> cdr = 
    
    lambda
    
     lst: lst[1:]
>>> sum2 = 
    
    lambda
    
     lst: car(lst)+car(cdr(lst))
>>> sum2(range(10))
1
>>> car = 
    
    lambda
    
     lst: lst[2]
>>> sum2(range(10))
5

>>> 
    
    from
    
     functional 
    
    import
    
     *
>>> let = Bindings()
>>> let.car = 
    
    lambda
    
     lst: lst[0]
>>> let.car = 
    
    lambda
    
     lst: lst[2]
Traceback (innermost last):
 File "<stdin>", line 1, 
    
    in
    
     ?
 File "d:\tools\functional.py", line 976, 
    
    in
    
     __setattr__
  
    
    raise
    
     BindingError, "Binding '%s' cannot be modified." % name
functional.BindingError: Binding 'car' cannot be modified.
>>> car(range(10))
0

>>> let = Bindings()   
    
    # "Real world" function names
>>> let.r10 = range(10)
>>> let.car = 
    
    lambda
    
     lst: lst[0]
>>> let.cdr = 
    
    lambda
    
     lst: lst[1:]
>>> eval('car(r10)+car(cdr(r10))', namespace(let))
>>> inv = Bindings()   
    
    # "Inverted list" function names
>>> inv.r10 = let.r10
>>> inv.car = 
    
    lambda
    
     lst: lst[-1]
>>> inv.cdr = 
    
    lambda
    
     lst: lst[:-1]
>>> eval('car(r10)+car(cdr(r10))', namespace(inv))
17

>>> 
    
    defa
    
    (n):
...   add7 = b(n)
...   
    
    return
    
     add7
...
>>> 
    
    defb
    
    (n):
...   i = 7
...   j = c(i,n)
...   
    
    return
    
     j
...
>>> 
    
    defc
    
    (i,n):
...   
    
    return
    
     i+n
...
>>> a(10)   
    
    # Pass cargo value for use downstream
17

>>> N = 10
>>> 
    
    defaddN
    
    (i):
...   
    
    global
    
     N
...   
    
    return
    
     i+N
...
>>> addN(7)  
    
    # Add global N to argument
17
>>> N = 20
>>> addN(6)  
    
    # Add global N to argument
26

全局变量 N 在任何希望调用 addN() 的时候起作用，但没有必要明确地传递全局背景“上下文”。另一个更 Python 专用的技术是将一个变量在定义时“冻结”入一个使用默认参数的函数：
清单 6. 显示冻结变量的 Python 部分

>>> N = 10
>>> 
    
    defaddN
    
    (i, n=N):
...   
    
    return
    
     i+n
...
>>> addN(5)  
    
    # Add 10
15
>>> N = 20
>>> addN(6)  
    
    # Add 10 (current N doesn't matter)
16

class
    
     TaxCalc:
  
    
    deftaxdue
    
    (self):
    
    
    return
    
     (self.income-self.deduct)*self.rate
taxclass = TaxCalc()
taxclass.income = 50000
taxclass.rate = 0.30
taxclass.deduct = 10000
    
    print
    
     "Pythonic OOP taxes due =", taxclass.taxdue()

class
    
     TaxCalc:
  
    
    deftaxdue
    
    (self):
    
    
    return
    
     (self.income-self.deduct)*self.rate
  
    
    defsetIncome
    
    (self,income):
    self.income = income
    
    
    return
    
     self
  
    
    defsetDeduct
    
    (self,deduct):
    self.deduct = deduct
    
    
    return
    
     self
  
    
    defsetRate
    
    (self,rate):
    self.rate = rate
    
    
    return
    
     self
    
    print
    
     "Smalltalk-style taxes due =", \
   TaxCalc().setIncome(50000).setRate(0.30).setDeduct(10000).taxdue()

from
    
     functional 
    
    import
    
     *
taxdue    = 
    
    lambda
    
    : (income-deduct)*rate
incomeClosure = 
    
    lambda
    
     income,taxdue: closure(taxdue)
deductClosure = 
    
    lambda
    
     deduct,taxdue: closure(taxdue)
rateClosure  = 
    
    lambda
    
     rate,taxdue: closure(taxdue)
taxFP = taxdue
taxFP = incomeClosure(50000,taxFP)
taxFP = rateClosure(0.30,taxFP)
taxFP = deductClosure(10000,taxFP)
    
    print
    
     "Functional taxes due =",taxFP()
    
    print
    
     "Lisp-style taxes due =", \
   incomeClosure(50000,
     rateClosure(0.30,
       deductClosure(10000, taxdue)))()