Toolz: A functional standard library for Python

Re:Toolz: A functional standard library for Python by mumblemumble on Thursday January 21, 2021 @08:25PM (#25867061)

I see you chopping the first two words off that quote. ;)

In this specific case, that single instance of a single pattern is such a throw-away that it doesn't deserve a name, but the pattern itself is easy enough to name. So I'd skip the single-purpose function and create a combinator.

  def do_each(*args):
    def helper(x):
      for fn in args:
        fn(x)
    return helper

and then, when I need to do both foo and bar, I don't even need a lambda.

  map(do_each(foo, bar), some_sequence)

That's a fairly specific case, though. Moving back to the general, I would say that a function that does more than one thing, but can't easily be named, is a code smell.

Of course, every general rule has its exceptions. But I'm not so keen on the idea of optimizing one's coding style for the exceptional cases. Going back to PEP 20, "Special cases aren't special enough to break the rules."

(I realize mapping a function that returns nothing is terrible, but I'm feeling too lazy to think of a better example.)

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Re:Toolz: A functional standard library for Python by uryga on Friday January 22, 2021 @04:34AM (#25870013)

i like a nice combinator as much as the next person! but consider this: if python already had multiline lambdas, would you be arguing for using a narrow-purpose combinator instead of `lambda x: foo(x); bar(x)`?

[this kind of reminds me of Go's generics mess, where workarounds for lack of generics are "just how you write Go and that's the language's philosophy"... until generics land and suddenly they won't be]

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Re:Toolz: A functional standard library for Python by mumblemumble on Friday January 22, 2021 @08:32AM (#25871486)

Probably. I think the former is more readable and, at the use site, more concise.

Regardless, I don't think the hypothetical is super useful, because its unstated major premise is, "But what if we, for the sake of argument, ignore all the other good reasons why Python doesn't have them?"

My favorite programming language is functional, and has significant whitespace and multiline anonymous functions. While it is my favorite, I do have to concede that the Python language maintainers' worries about the syntactic implications of multiline lambdas in a whitespace language are accurate.

(I could quote the zen of python some more here, too. Lines 5 and 6.)

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