I started reading David Mertz's book today 'Text Processing in Python.' While he has a fairly terse description of Lambda's the examples in the first chapter combined with the explanation in Appendix A made them jump off the page for me (finally) and all of a sudden I understood their value. That is not to say his explanation will work for you and I am still at the discovery stage so I will not attempt to add to these responses other than the following: I am new to Python I am new to OOP Lambdas were a struggle for me Now that I read Mertz, I think I get them and I see them as very useful as I think they allow a cleaner approach to programming.

He reproduces the Zen of Python, one line of which is Simple is better than complex. As a non-OOP programmer reading code with lambdas (and until last week list comprehensions) I have thought-This is simple?. I finally realized today that actually these features make the code much more readable, and understandable than the alternative-which is invariably a loop of some sort. I also realized that like financial statements-Python was not designed for the novice user, rather it is designed for the user that wants to get educated. I can't believe how powerful this language is. When it dawned on me (finally) the purpose and value of lambdas I wanted to rip up about 30 programs and start over putting in lambdas where appropriate.

我不能说python对lambda的具体实现，但一般来说lambda函数真的很方便。它们是函数式编程的核心技术(甚至是技术)，在面向对象程序中也非常有用。对于某些类型的问题，它们是最好的解决方案，所以当然不应该忘记!

我建议你仔细阅读闭包和map函数(它链接到python文档，但它存在于几乎所有支持函数结构的语言中)，看看它为什么有用。

使用lambdas的一个有用的例子是提高长列表推导式的可读性。 在这个例子中，loop_dic是为了清晰起见的缩写，但是假设loop_dic非常长。如果你只是使用一个包含i的普通值，而不是该值的lambda版本，你会得到一个NameError。

>>> lis = [{"name": "Peter"}, {"name": "Josef"}]

>>> loop_dic = lambda i: {"name": i["name"] + " Wallace" }
>>> new_lis = [loop_dic(i) for i in lis]

>>> new_lis
[{'name': 'Peter Wallace'}, {'name': 'Josef Wallace'}]

而不是

>>> lis = [{"name": "Peter"}, {"name": "Josef"}]

>>> new_lis = [{"name": i["name"] + " Wallace"} for i in lis]

>>> new_lis
[{'name': 'Peter Wallace'}, {'name': 'Josef Wallace'}]

你可以用lambda做的任何事情，都可以用命名函数或列表和生成器表达式做得更好。

因此，在大多数情况下，在任何情况下您都应该只使用其中一种(可能除了在交互式解释器中编写的草稿代码)。

lambdas在GUI编程中非常有用。例如，假设您正在创建一组按钮，并且希望使用单个参数化回调，而不是每个按钮使用唯一的回调。Lambda让你轻松完成:

for value in ["one","two","three"]:
    b = tk.Button(label=value, command=lambda arg=value: my_callback(arg))
    b.pack()

(注意:虽然这个问题是专门问lambda的，但你也可以使用functools。以获得相同类型的结果)

另一种方法是为每个按钮创建单独的回调，这可能导致重复的代码。

Lambda是一个过程构造函数。你可以在运行时合成程序，尽管Python的lambda不是很强大。请注意，很少有人理解这种编程。