[reikonomusha]

I agree.

Haskell enforces a programmer to create structure. There's no way around it. And it's (nearly) impossible to hack things together without failing early and often.

As a result, before the problem you're trying to solve can be explored, you're stuck making guesses on how the problem should even be structured. You spend a few hours with one guess, it turns out to not get your far, and you try another.

The unfortunate part is that these guesses aren't letting you get to the meat of the problem effectively; you're stuck trying to solve a meta-problem.

Of course, once you have solved the meta-problem well enough, you can start exploring your problem. Unfortunately, you may find that your meta-solution doesn't actually let you answer questions you didn't know you wanted to answer from the get-go, and now you're back to square-one.

When everything is right, the program is usually very beautiful, safe, and—if you're skilled enough—efficient.

Perhaps not all Haskell programmers have this issue for very non-trivial programs, though I certainly do.

[lclarkmichalek]

I don't really agree. The greatest structure in most of my Haskell programs is some kind of ErrorT or something. That requires me to structure the way I handle IO and the way that Errorable things happen, but beyond that, `a` is just as generic as any Python type. Sure, a lot of libraries do require you to accept certain premises, which may be a problem, but most of them provide ways to break out of their abstractions: ErrorT provides `runErrorT :: (Monad m, Error e) => ErrorT e m a -> m (Either e a)` which allows me to break out very easily, and due to the composable nature of Haskell, even if the library does not provide a function, it is often far from hard to write one yourself.

[tinco]

I agree that Haskell forces the programmer to create structure, but I don't agree with your meta-problem hypothesis. I think the structure actually is a big part of the real problem, and Haskell just prevents you from implementing incomplete or incorrect solutions.

Those solutions might in another language require a hack or leaky abstractions to work, if they would be possible to get to work at all.

I've walked into problems like the OP has before with Haskell, and when there seems to be no nice way of defining a type structure to model the problem, it usually meant that the idea in my head had a fundamental problem. If I look at this tree I get the feeling that perhaps he just has two problems, and he's looking at it like he's got only one.

And once you do get your type structure neatly in place, often times the implementation will just flow out of your fingertips. And when it does, it will be powerful, flexible and robust.