One-lined Python

sp332 | karma 55607 | avg karma 2.75 · 2019-08-21 14:25:10+00:00

The demo at the top doesn't work because it's expecting python 3 but the demo code is python 2.

trymas | karma 2531 | avg karma 3.93 · 2019-08-22 09:50:16+00:00

Even if fixed to python 3, still throws an error:

> Your code could not be one-lined. name 'reduce' is not defined

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np_tedious | karma 1068 | avg karma 2.46 · 2019-08-22 10:15:31+00:00

Python3 put it in functools, I think. Ah the need for an import would prevent one lining.

Never quite understood that decision

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gvx | karma 384 | avg karma 2.58 · 2019-08-22 10:29:15+00:00

Reduce isn't used much. Things that tend to use reduce in languages like Haskell tend to be built from other primitives in Python.

Instead of reduce, you could use https://docs.python.org/3/library/functions.html#__import__

    __import__('functools').reduce

jmmcd | karma 1243 | avg karma 2.43 · 2019-08-22 13:05:16+00:00

The article goes on to use `__import__()` to one-line imports.

obenn | karma 289 | avg karma 3.66 · 2019-08-22 11:06:44

Neat, I just learned what the Y combinator actually is!

virusduck | karma 264 | avg karma 1.59 · 2019-08-22 14:54:51+00:00

I want this to work so badly. Sadly, I think the Python on the website is committing seppaku rather than being forced to abuse its brethren.

gustavorg | karma 210 | avg karma 4.12 · 2019-08-22 16:00:36+00:00

I believe is Seppuku (https://en.wikipedia.org/wiki/Seppuku)

virusduck | karma 264 | avg karma 1.59 · 2019-08-22 16:14:26

I believe it is ??, but ok.

pixelbath | karma 1288 | avg karma 3.07 · 2019-08-22 22:25:50

"Seppuku" is the accepted romanization of ??; why does it seem incorrect to you?

olooney | karma 2229 | avg karma 7.38 · 2019-08-22 14:56:07

I like this. Here is a one-liner I wrote recently that calculates the 10th Fibonacci number:

    (lambda n: n(lambda x: x+1)(0))(((lambda f: (lambda x: x(x))(lambda y: f(lambda z: y(y)(z))))(lambda f: (lambda f: lambda n: (lambda f: lambda x: x) if (lambda b: b(True)(False))((lambda n: n(lambda x: (lambda x: lambda y: y))(lambda x: lambda y: x))(n)) else f(n))(lambda n:(lambda m: lambda n: (lambda m: lambda n: (lambda n: n(lambda x: (lambda x: lambda y: y))(lambda x: lambda y: x))((lambda m: lambda n: n((lambda n: lambda f: lambda x: n(lambda g: lambda h: h(g(f)))(lambda u: x)(lambda u: u)))(m))(m)(n)))((lambda n: lambda f: lambda x: f(n(f)(x)))(m))(n))(n)((lambda n: lambda f: lambda x: f(n(f)(x)))(lambda f: lambda x: f(x)))(n)((lambda m: lambda n: lambda f: lambda x: m(f)(n(f)(x)))(f((lambda m: lambda n: n((lambda n: lambda f: lambda x: n(lambda g: lambda h: h(g(f)))(lambda u: x)(lambda u: u)))(m))(n)(lambda f: lambda x: f(x))))(f((lambda m: lambda n: n((lambda n: lambda f: lambda x: n(lambda g: lambda h: h(g(f)))(lambda u: x)(lambda u: u)))(m))(n)((lambda n: lambda f: lambda x: f(n(f)(x)))(lambda f: lambda x: f(x)))))))))(lambda f: lambda x: f(f(f(f(f(f(f(f(f(f(x))))))))))))

Paste that into a Python 3 interpreter, you should see "55". Somewhere in there is the Y-contaminator and several other tricks similar to what this article describes.

xamuel | karma 3424 | avg karma 3.05 · 2019-08-22 16:01:34+00:00

If you like that sort of thing, try doing similar code for the Ackermann function [1]. In a certain sense that can be made semi-formal, if you can do this sort of thing for the Ackermann function, then you can do it for almost anything.

https://en.wikipedia.org/wiki/Ackermann_function

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sethgecko | karma 218 | avg karma 1.82 · 2019-08-22 15:08:42

If you want your mind to blow up I recommend watching this year's "Lambda Calculus from the Ground Up" PyCon talk by the wizard David Beazley https://www.youtube.com/watch?v=pkCLMl0e_0k

kiddico | karma 683 | avg karma 2.56 · 2019-08-22 15:30:15

Followed by watching the rest of his videos! Each one is gold.

pohl | karma 9288 | avg karma 3.55 · 2019-08-22 17:25:27+00:00

No newlines allowed. No semicolons, either.

In my head I read this in the voice of Harry Dean Stanton (Repo Man).

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RocketSyntax | karma 289 | avg karma 0.64 · 2019-08-22 21:30:26

great for submitting complex one liners via docker exec