I think the GP's point was that functional languages give you similar benefits, but with more uniform and disciplined behavior of many language features. Why FP is not more widely used compared to imperative language is another topic though.

I love JS because it's flexible and doesn't lock me into a paradigm. I can be as strict as I want to be. In the end, I think it depends on how someone thinks about problems. I tend to bend my thinking depending on the type of problem and how I might optimally solve said problem. When I need something else (often for performance), I'll circle around at that point for that part.

for example, in all three languages above, expressions are much easier to understand because they always return a value. this makes code easier to reason about. this is not true in python.

the languages i mentioned do have static typing but they have type inference. so you get the best of both worlds. you do need to type annotate at some points to clarify things, but this isn't a problem as it documents to both the user and compiler.

given your above reasons, you owe it to yourself to learn an ml. there is the programming languages course on coursera by dan grossman, which uses sml in the first part, and the ocaml mooc just started where you still have time to register and complete it.

https://www.coursera.org/learn/programming-languages

https://www.fun-mooc.fr/courses/course-v1:parisdiderot+56002...

F# has curly braces. Also, as you say, it requires some type annotations.

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.)

> expressions are much easier to understand because they always return a value. this makes code easier to reason about. this is not true in python

Huh? Python expressions always return a value.

Perhaps what you mean is that Python also has statements, which do not return a value, whereas these languages do not--everything is an expression, as in Lisp?

> you owe it to yourself to learn an ml

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 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"

  test(2)

> 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.

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.

> 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

True

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

  test(2) is None

    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

    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

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'

    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'