Comment by Ingon | Hacker News Reader

Comment by Ingon | Hacker News Reader

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This looks like an attack to functional programming mainly. And if you follow Haskell closely I think that the guys building it are well aware that the world is actually full of side effects. But the thing is that if they push the "pure" ideology to its limits they will uncover a number of useful things along the way. And that is the whole reason to stick to it. Maybe you don't find the usefulness of monads, but that doesn't mean that there is no value of composing part of you programs in this way. Otherwise you are stuck to the same old ways of doing things.

So going with pure has its benefits for all of us, but this does not mean that we should stick with something just because. Unfortunately the answer to most of the questions in programming/software development is: it depends.

> This looks like an attack to functional programming mainly.

I don't know. People call many languages (F#, Clojure...) functional even though they have no separation between pure and impure code. So it's mostly an attack against Haskell.

Which is not entirely unwarranted, I have to say. While monads are fairly straightforward, stacks of monad transformers are frankly a pain, and error handling is miserable. It does not make the whole idea useless, but I think the way forward is to separate the effect system from the type system. However, hand-waving it with "just use static analysis" is not, I think, a panacea. It's very useful documentation for the programmer, and helps to organize your code (in fact, it's usually a good idea to do that even in OO-languages). And it does not take into account the extremely powerful things it gives you. Early termination without exception handling, powerful and easy parallelism for pure code, etc.

> But the thing is that if they push the "pure" ideology to its limits they will uncover a number of useful things along the way.

For example new elegant approaches to parallelism/concurrency that would be very difficult in an impure language.

Indeed. For instance, something like

http://hackage.haskell.org/package/parallel-3.1.0.1/docs/Con...

Would be very difficult to implement in a language that is not referentially transparent and lazy.

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