'Is it a bad practice writing long one-liner code?

I found myself keep writing pretty long one-liner code(influenced by shell pipe), like this:

def parseranges(ranges, n):
    """
    Translate ":2,4:6,9:" to "0 1 3 4 5 8 9...n-1"
               == === ==      === ===== =========
    """
    def torange(x, n):
        if len(x)==1:
            (x0, ) = x
            s = 1 if x0=='' else int(x0)
            e = n if x0=='' else s
        elif len(x)==2:
            (x0, x1) = x
            s = 1 if x0=='' else int(x0)
            e = n if x1=='' else int(x1)
        else:
            raise ValueError
        return range(s-1, e)
    return sorted(reduce(lambda x, y:x.union(set(y)), map(lambda x:torange(x, n), map(lambda x:x.split(':'), ranges.split(','))), set()))

I felt ok when I written it.
I thought long one-liner code is a functional-programming style.
But, several hours later, I felt bad about it.
I'm afraid I would be criticized by people who may maintain it.
Sadly, I've get used to writing these kind of one-liner.
I really want to know others' opinion.
Please give me some advice. Thanks

coding-style


Solution 1:[1]

(Update 2022-03-25: My answer refers to a previous revision of the question.)

The first and third examples are acceptable to me. They are close enough to the application domain so that I can easily see the intention of the code.

The second example is much too clever. I don't even have an idea about its purpose. Can you rewrite it in maybe five lines, giving the variables longer names?

Solution 2:[2]

I would say that it is bad practice if you're sacrificing readability.

Solution 3:[3]

It is common wisdom that source code is written once but read many times by different people. Therefore it is wise to optimize source code for the common case: being read, trying to understand.

My advice: Act according to this principle. Ask yourself: Can anybody understand any piece of my code more easily? When the answer is not a 100% "No, I can't even think of a better way to express the problem/solution." then follow your gut feeling and reformat or recode that part.

Solution 4:[4]

Unless performance is a major consideration, readability of the code should be given high major priority. Its really important for its maintainability.

A relevant quote from the book Structure and Interpretation of Computer Programs.

"Programs should be written for people to read, and only incidentally for machines to execute."

Sources

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Source: Stack Overflow

Solution Source
Solution 1
Solution 2 Mansoor Siddiqui
Solution 3 A.H.
Solution 4 M S

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