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Comment by visarga | Hacker News Reader

Functional looks good for applying x^2 to a list of numbers, but when you need to do something a little more complex, it becomes hard to put in in a single line/lambda.

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You decompose the complex task into separate other tasks and compose them together the same way that you would in any other paradigm. You wouldn't expect to express a complex task in a single line in an OO program for example.

documents = filter(pdf, folder)

summaries = map(summarise_document, documents)

Is pretty clear despite summarising a document being a complex task.

I appreciate how nice the functional style is, but sometimes a for loop acting over a few local variables is simpler to read than a bunch of map's and lambdas. Does this look readable and nicer to you than a for loop?

    print pipeline_each(bands, [call(lambda x: 'Canada', 'country'),
                                call(lambda x: x.replace('.', ''), 'name'),
                                call(str.title, 'name'),
                                extract_name_and_country]

Sometimes it's easier to implement directly what you want done than to remember the name of the function that plucks a field from a list of records or something like that.

You seem to be obsessed with this idea that "functional programming" is a fancy term for squishing your entire program onto one line via gratuitous use of anonymous functions, which simply isn't true. I don't know what this snippet of code is supposed to do, and it's not very pretty, but guess what: it is just as easy to produce unreadable garbage in an "imperative style". I've seen a lot of both, but more of the latter.

Oh, it's good for so much more. Just take this refactoring of a functional test library of mine:

1. https://github.com/haf/expecto/commit/e4f2ce3cc2b2cf3c848c5e... 2. https://github.com/haf/expecto/commit/9f8380cdb17002e09ae169... 3. https://github.com/haf/expecto/commit/3fafd9ada4e932dcadc24a... 4. https://github.com/haf/expecto/commit/0c243c9eb781e7527b0bd2... 5. https://github.com/haf/expecto/issues/36 6. https://github.com/haf/expecto/commit/9284173599145a1bb08ee8...

Functional programming also makes for really smooth control flow and that's a huge part of programming. In short what it does, is give you the ability to compose and reason with your code.

That's why one should use more than a single one-line function per program.

That's fine, that's not really one of the points to functional programming.

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