Monday, January 11, 2010

What's Missing in the Haskell Community?

Documentation is often sighted as possibly the #1 item that needs to be improved with respect to Haskell. It depends on what modules we use, but I have to agree. It's quite difficult to uphold the claim that you don't need to understand Category Theory in order to employ a Monoid or Monad, but when you run into Monoid instances like "endo" and don't know what to make of it because the documents don't really describe how to use it, you're probably going to suffer in that that implementation of Monoid is likely useful for some kind of programming that you want to do, and you'll end up struggling with a solved problem. Some people have been stepping up to improve the documentation, and that's really wonderful, but I think there's still some work to be done there.

The best way to learn Haskell in general for me has been to get the great books that are available out there. Real World Haskell is freely available online. (But please support the authors and get a copy if you're finding it useful). Search for Haskell on and you'll find that the reviews are a really good guide to picking which ones might be right for you. If you're really new to the language. Dr. Graham Hutton's book is outstanding. There's even been a series on MSDN's channel 9 walking through the chapters of this book, explaining how to solve some problems and think like a functional programmer.

To keep up to date with Haskell developments, reddit has been invaluable. You'll find blog posts, updates about new Haskell packages, and general community news and related discussion topics there.

So what's still missing?

I can tell you that over the years I've been messing around with Haskell, trying to understand how it works, why it's appropriate for certain kinds of problem solving, and to really get a good appreciation of why people seem to really like it so much, that I feel like the community has been pretty amazing with respect to fueling the flames of curiosity.

Where I think we might be needing a little more help is in the following areas of Haskell.

Explaining where laziness or non-strict evaluation is an advantage over strict evaluation. Perhaps this requires learning to think about the code we write differently, in much the same way it can be a leap to get to recursive programming, I feel this might be a slightly wider gap to cross mentally. (But then again maybe I'm just getting old... )

Show more examples of unintended data-growth or space leakage due to the lack of strict evaluation. In languages like C, you're in direct control of when memory is allocated or deallocated. This is generally considered a "bad thing" for a lot of tasks, including systems programming if you are signed up with the Go camp. A side effect of non-strict by default seems to be that you have to understand how the code you're writing will be evaluated from a bit of a wider view than you might need to care about malloc and free, or new or delete. It seems that unless you've somehow been taught how to recognize the patterns that could cause a a space leak, you're basically doomed to run into some sharp corners that others already seem to understand how to avoid.

Real World Haskell has a great chapter on optimization, but perhaps it's time for an "Optimizing Haskell" book too? There's lots of good advice scattered all over the web, and the experts are not shy to offer you help should you ask. Sometimes I think it's difficult to even ask the right questions when you're confused though, and I suspect this may turn some folks off to Haskell.

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