Stop writing lambda expressions in Python

Re:Stop writing lambda expressions in Python by nikofeyn on Thursday September 27, 2018 @06:17PM (#18089307)

okay, f# has curly braces. but not in the sense of other C-like languages like c++, java, and c#. they are primarily used for sequence expressions and computation expressions like async.

> I see that F# has a REPL, but it seems bolted on as an afterthought instead of being an integral part of the language. (Also, it's not clear whether the REPL is available in Mono on Linux. I am allergic to Windows and anything built by Microsoft.)

well that first sentence is simply not true, and i don't know what gave you that impression. f#'s repl, f# interactive, is available on linux through mono and will soon be available through .net core. i can't help you being needlessly allergic to a major operating system or company. f# came out of microsoft research.

> Huh? Python expressions always return a value.

they do? take:

  def test(x):
    "something"

so what does

  test(2)

return?

> I don't owe it to myself to learn anything unless I decide to. I wasn't trying to convince anyone else to use Python; I was just giving reasons why I like Python. Please extend me the same courtesy when you talk about things you like about your favorite languages.

i don't know why you're upset. i am not for sure where i was discourteous. i didn't mean anything by my statement other than to check out the languages and courses (the coursera one is very good). if those are your reasons for python, i just thought you would honestly like an ML-based language. i just used "owe it to yourself" as an expression, which apparently came out wrong through text. of course you don't owe anyone anything. i was just making a suggestion.

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Re:Stop writing lambda expressions in Python by pdonis on Thursday September 27, 2018 @08:26PM (#18090040)

> of course you don't owe anyone anything

Yes, and thanks for acknowledging that. But then the phrase "owe it to yourself" didn't really communicate your intent correctly, which is why I objected to it.

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Re:Stop writing lambda expressions in Python by firefwing24 on Thursday September 27, 2018 @06:41PM (#18089495)

Replying to your reply of the child comment:

> i guess that is true in python3 but it is not in python 2.7.

No, it's always been there.

    >>> def f():
    ...     pass
    ...
    >>> f() is None
    True

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Re:Stop writing lambda expressions in Python by codexon on Thursday September 27, 2018 @06:27PM (#18089380)

>>> test(2) is None

True

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Re:Stop writing lambda expressions in Python by nikofeyn on Thursday September 27, 2018 @06:34PM (#18089435)

i guess that is true in python3 but it is not in python 2.7.

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Re:Stop writing lambda expressions in Python by xapata on Thursday September 27, 2018 @06:39PM (#18089482)

False. You're just not familiar with how the REPL works.

    >>> None
    >>> print(None)
    None

In the future, you might want to refrain from strong criticism of a thing you're not familiar with. That habit leads to all sorts of -isms.

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Re:Stop writing lambda expressions in Python by nikofeyn on Thursday September 27, 2018 @07:54PM (#18089884)

i do know how the repl works. i explicitly tried it out. i defined the function just as i said and ran

  test(2) is None

and got false. i just now went to try it out again at home and got true. i don't know what to tell you other than something must have got shadowed somewhere.

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Re:Stop writing lambda expressions in Python by pdonis on Thursday September 27, 2018 @08:22PM (#18090018)

Here's what I get from the Python 3 REPL:

    peter@localhost:~$ python3
    Python 3.5.2 (default, Nov 23 2017, 16:37:01)
    [GCC 5.4.0 20160609] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> def test(x):
    ...     "something"
    ...
    >>> test(2) is None
    True

And Python 2:

    peter@localhost:~$ python
    Python 2.7.12 (default, Dec  4 2017, 14:50:18)
    [GCC 5.4.0 20160609] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> def test(x):
    ...     "something"
    ...
    >>> test(2) is None
    True

If you post such a transcript from your REPL session where you get False, it should be easier to tell what's different between your setup and mine (which is a stock Python install on Ubuntu 16.04).

However, there is another even more direct experiment you could have run at the Python REPL to see what Python expressions return: just type the expression directly at the REPL and see what it prints back at you. In Python 3:

    peter@ToshibaSatellite:~$ python3
    Python 3.5.2 (default, Nov 23 2017, 16:37:01)
    [GCC 5.4.0 20160609] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> "something"
    'something'

And in Python 2:

    peter@ToshibaSatellite:~$ python
    Python 2.7.12 (default, Dec  4 2017, 14:50:18)
    [GCC 5.4.0 20160609] on linux2
    Type "help", "copyright", "credits" or "license" for more information.
    >>> "something"
    'something'

So, in your test function above, the expression "something" does return itself; it just does it inside the function, and that return value then gets thrown away when the function exits, because you didn't return it from the function itself.

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Re:Stop writing lambda expressions in Python by nikofeyn on Saturday September 29, 2018 @04:49PM (#18102727)

i know how to use the repl. i moved between computers during comments and wasn't able to inspect my repl session where it originally returned false. as i mentioned, i must have redefined something or shadowed something which caused confusion, and i just didn't realize it at the time.

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