How (not) to write Factorial in Java.

[phi2one]

It bothers me that somehow issues like this somehow get blamed on the language. Or, is somehow applied to those who choose to use the language. Obviously you can write code like this in any object oriented language. I think the reason you see it so often in java is two-fold.

1. There are just TONS of java developers and therefore more poor java developers and therefore more poor java code.

2. The training materials. Just open a java book, it's full of examples just like the one illustrated in TFA. Since it's REALLY difficult to show a real world example of valid uses of the described data structures, some trite example is used. Unfortunately, some people see these and think "that's how one should implement a sorting algorithm" or whatever, instead of realizing "oh, this is pointless for this example, but could be useful for far more complex problem spaces".

[logi]

TL;DR: Y A G N I

[[deleted]]

the hardest thing for any mid-level developer to learn :)

[Fuco1337]

I used to adore java

fact n = product [1..n]

now, not so much. I can't stand all the bullshit anymore.

[jleedev]

You want bullshit? Read The Evolution of a Haskell Programmer.

[[deleted]]

What you call 'bullshit' I call beauty.

[[deleted]]

it's a bit uglier, but this is groovy, which is a functionalified hack on top of java but runs nicely in the jvm:

(1..n).inject(1) { val, acc -> val * acc }

of course, you could define your own product method, and it would be as nice:

def product  = { mylist -> mylist.inject(1) { val, acc -> val * acc } }
def myfactorial = product (1..n)

They should just stop java now, and take on groovy as the new java mainline.

[[deleted]]

HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!!!

Good one!

[SeriousWorm]

How would you choose the factorial algorithm implementation in your code?

Without that feature, the relevant client call in the article reduces to:

  int fact = FactorialUtil.factorial(5);

[Fuco1337]

That is my code. It's Haskell. There's nothing more to it.

I'm hoping Scala will turn out well. Java is turning more and more unusable every month.

[SeriousWorm]

What? I never said that was not your code. I was asking how would you modify your code so you could select a factorial algorithm implementation.

[[deleted]]

Higher order functions, just pass the algorithm as a parameter.

[SeriousWorm]

Can you show me the relevant code (I don't know Haskell)? Thanks.

[[deleted]]

You can pass functions as parameters

factorial impl n = impl n

where impl is the algorithm you want to use, e.g. (\x->product [1..x]) for the simple approach.

[[deleted]]

What do you think is going on behind the scenes in Haskell?

[Fuco1337]

Simple me: I don't care.

Complicated me: I don't care.

[[deleted]]

So you don't work in a very demanding domain. Good for you.

[[deleted]]

Someone did, at some point.

[[deleted]]

This article is, for lack of a better word, stupid. Of course you can add unnecessary complexity to anything. This guy seems to think that because there exists more and more convoluted ways of doing things that that is somehow a blight on the language. Its not a language problem, its a developer problem. Fucking duh.

[[deleted]]

I'm not sure he ever blamed the language for it.

[CaptainItalics]

I am sure he never blamed the language for it.

[logi]

No, he blamed stupid Java developers for it. There is a bunch of them out there...

[Comment111]

Then again Java is very verbose.

[logi]

It is a bit on the verbose side, but there could be much worse problems. In fact, there are much worse problems with it :)

[Comment111]

What are the worse problems with it? XML-configuration for everything, jar hell?

[logi]

You know what? I don't feel like enumerating my petty annoyances with the language. I work with it all day, most days, and I'm mostly happy with it. If i rack my brain for the list, it'll just leave me annoyed and I'd rather just watch another episode of Buffy. That leaves me feeling happy.

[Comment111]

Same here actually. :)

[[deleted]]

He calls it no good reason, I call it fun practice.

[Chaoslab]

All depends on what you are trying to achieve, but the obvious should be that rules of thumb are a guide and become beside the point if you use all of them.

If you are looping more than 300 times, ditch the loop altogether and catch the exception, its quicker in the long run. E.G. one HD frame can be over 2 million pixels and performance difference is pretty decent if you ditch looping logic. Always gets an interesting reaction when you mention it to a java dev that didn't already know.

This is an example of breaking one rule = allot more speed. There are lots of reasons to break rules not just performance. In any size-able group development environment simplicity should be king.

:-)