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Comment by KirinDave | Hacker News Reader

I couldn't help but feel irritated by this document. It's cute and all, but it implies Python is somehow unique—culturally or technologically—in grasping at these concepts. You could easily have written this as a Ruby or Scheme manifesto with nearly identical wording and had a valid message.

And then, in our very first example, there is a use of lambda, a misnomer of a concept Python doesn't really support? My brow furrowed slightly more.

I can't help but feel like these people are celebrating their investment in their tools rather than the virtues of the tools themselves.

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You could easily have written this as a Ruby or Scheme manifesto

Yes, but this practically is the Python manifesto.

I'm saying it's also the Scheme manifesto.

Nobody is saying that this advice is unique to Python. Feel free to use it for Visual Basic too if you want.

It might be also the Scheme manifesto, but in Python its so deep rooted in the community that its practically embedded in the language itself:

Python 2.6.5 (r265:79063, Oct 28 2010, 20:56:23)

[GCC 4.5.0 20100604 [gcc-4_5-branch revision 160292]] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> import this

The Zen of Python, by Tim Peters

Beautiful is better than ugly.

Explicit is better than implicit.

Simple is better than complex.

...

The first section is pointing out list comprehensions as a better syntax than lambda, I believe. Also, the zen of python has been around for a long time: http://www.python.org/dev/peps/pep-0020/.

There's an import statement that will print it I believe, but I'm not sure exactly what it is.

$ python -c "import this"

It's a better syntax than Python's 10-year-out-of-date notion of lambda. For example, this is what a more modern language does with lambdas:

    numbers.filter( _ % 2 == 0 )

This document is old, so we can probably excuse it... but how many Python folks know that?

What is the language?

  numbers.filter( _ % 2 == 0 ).map( _ / 2 )

Zen of Python doesn't contain any lambdas (the link from the grandparent http://www.python.org/dev/peps/pep-0020/ ). List Comprehensions are 10 years old http://www.python.org/dev/peps/pep-0202/

How do you write:

  lambda x, y=1: x+y
  lambda *args: reduce(lcm, args)
  lambda **kwargs: kwargs.get('a') or kwargs.get('b')

  def lcm(a, b):
      return a*b // gcd(a, b)

  def gcd(a, b):
      while b:
          a, b = b, a % b
      return a

The link for the thread: http://artifex.org/~hblanks/talks/2011/pep20_by_example.py.t...

It does indeed mention a lambda in the very first example, if only as a competition with list comprehension syntax. But even Python's list comprehensions look a little dated now.

Python's list comprehension is actually inspired by Haskell (or was it the other way around)?

What do you mean by dated? What new ideas have come up for List comprehension syntax?

(I agree that Lambda should be call fun or fn or \. An implicit _ might also work, though that's somewhat against Python's spirit---c.f. the explicit self in methods.)

Like most good ideas, it came from Haskell :)

The part that bothers me about the list comprehension section is that conflating list comprehension and lambda. Is it telling me that list comprehension is better than map/filter or better than lambda? I don't know. Quiet honestly, in many situations I find:

halves_evens = lambda nums : [i/2 for i in nums if nums % 2 == 0]

to be the cleanest.

scala.

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