[sabellito]

Not trying to start anything, but what's functional about Python? It doesn't have/support tail recursion, a strong type system, pattern matching, immutability-by-default for lists and dictionaries.

From where I'm standing, python has some features that kinda look like functional programming concepts, but overall is an OO imperative language, like Ruby and many others.

My understanding for its preference from the DS community is due more for its library support in that domain.

[c3534l]

> strong type system, pattern matching, immutability-by-default for lists and dictionaries

As a side note, its really interesting just how much the popular conception of "functional" has changed. 10 years ago, I don't think anyone would have listed any of those as being important or suggestive of functional programming. Nowadays, "functional" means "like Haskell" instead of "like Lisp." I think we need to be careful when we talk about functional programming because so many ideas have jumped the paradaigm and it means so many different things to different people.

[reikonomusha]

Scheme and Standard ML standardized these very features in the 70s and 80s as a part of the “functional programming” paradigm.

[skissane]

Scheme doesn't have a "strong type system", "pattern matching", or "immutability-by-default".

Scheme didn't standardise those very features in the 70s and 80s – it still doesn't have them.

Some of those features are available in add-on libraries or as extensions in some specific Scheme implementations, but they are thus far absent from the standardised language.

[thayne]

That's true, but python isn't really functional in the "like lisp" way either. Things like ifs, loops, etc. are statements, not expressions. Lambdas are pretty limited (they can only be one line). There is no tail recursion.

Functions are first-class objects, and it supports higher-order functions, and had closure (even if in any non-trivial case you needed a full nested def) which were less common features when Python was first introduced, and probably why python was labeled as "functional." But now those are standard features in almost every modern language, so using that as a criteria for "functional" languages is not a very useful distinction.

[gilch]

No, Python's lambdas can have as many lines of code as you please. They are not limited to one line.

I'm not sure where this myth comes from, but I see it a lot. Maybe some people think that "lines of code" == "statements", but these are not remotely the same thing, even if they happen to coincide in simple cases.

Python's lambdas are limited to one expression in the implied return statement, but not allowing multiple statements in lambdas is no real limitation when programming in the functional style, as the true functional languages have no statements to speak of, only expressions, and their lambdas work exactly the same way Python's does. A single expression is all that a functional programming language's lambda needs.

Multiline lambdas are considered poor style in Python ("Why not use a `def`?" they'd say.), so you may not see them much, but they do work. The Hissp compiler, for example, relies on this feature. (I am the author of Hissp BTW.)

[daturkel]

Python is not fully a functional programming language but it supports some functional patterns. There's a nice mini-ebook by David Mertz on functional programming in Python, and it used to be freely available but I can't find it at the moment. However, he wrote an article version here: https://developer.ibm.com/languages/python/articles/l-prog/

Also, pattern matching is coming to python in 3.10. You can read about it here: https://www.python.org/dev/peps/pep-0634/

[nautilus12]

Dry python returns library gets pretty close to feeling like scala cats. Unproductive diversions and all.

[crazypython]

> a strong type system

It's a myth that dynamic languages can't have strong types. Python aborts almost immediately whenever it can. For instance, adding a number to a string? Exception. Accessing undefined properties?

Furthermore there's a language-standard static type checker, mypy.

> pattern matching

We have that in Python 3.10.

> immutability-by-default for lists and dictionaries

We do have tuples and frozendict.

Arguably its implementations of functional features are much weaker than "truly" functional ones such as Lisp, Haskell, OCaML or F#.

[Can_Not]

> Python aborts almost immediately whenever it can

doesn't sound very strong

[moron4hire]

Runtime type checking is most definitely not what people mean when they talk about strong type systems.

[reikonomusha]

Strong != static.

[ewi_]

I love python, and I don't know if the GP are good points, but your answer is really disengenuous.

> > pattern matching

> We have that in Python 3.10.

> > immutability-by-default for lists and dictionaries

> We do have tuples and frozendict.

3.10 like the version that is not released yet?

Tuples an frozendicts, so precisely non default list and dicts?

[mypalmike]

The tools are there but you don't like their names.

[c-cube]

Neither tuples nor frozen dicts offer efficient (logarithmic or constant time) updates, like lists or balanced trees or HAMT do. You can't really write a program with only immutable structures in python, unless you accept it will be unbearably slow, even for python. Clojure, erlang, elixir, these are dynamically typed and functional.

[Nican]

I think the appeal is with Jupyter [1] notebooks. Python is not about performance. Usually numpy (or other libraries) that does the heavy lifting on another language anyway.

But having the Jupyter notebooks allows for intractability with the data. Make changes, and see how it affects every step after it.

[1] https://jupyter.org/

[yashap]

- map/reduce/filter/for-comps in the standard library. Go doesn't support this style of programming, and because of the lack of generics, you can't write generic data structures with these types of methods either. It's all loops and mutation in Go

- first class functions. Go does have these

- concise lambda syntax, that makes them nice/easy to use. Go has first class functions, but a very verbose/awkward lambda syntax

- can easily create your own generic data structures with functional interfaces (can't do this in Go b/c no generics)

- Python is pretty strongly typed, and if you meant statically typed, there's now optional static type checking in Python, similar to TypeScript (not as robust/well implemented though)

- Python has decent immutability support. For example, dataclasses (https://docs.python.org/3/library/dataclasses.html) with frozen=True are a lot like immutable classes in more purely functional languages (i.e. case classes in Scala). Tuples and named tuples. There are libs out there for frozen (a.k.a. immutable) dicts, lists, etc.

- Python is about to get pattern matching in 3.10

- functools (https://docs.python.org/3/library/functools.html)

- etc.

You can absolutely use Python in a very mutable-OO style, but it also has pretty good functional programming support. If you look at most Python data science code, it's written pretty functionally.

I'd say most important for data science applications is the ability to create generic data structures with functional interfaces - you can't do this in Go, makes it really awkward to write a lot of the foundational vector, data frame, etc. libraries, that basically all higher level data science libs depend on.

[quixoticelixer-]

Functional languages don't need a strong type system