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Any Haskell web-application framework is awesome - Yesod in particular as it has the most active community and written material for it. I've lately been workin

• pekk 14y ago
  The correct way to use Python is to write unit tests. Don't blame your tools when you don't know how to use them correctly.
  • batgaijin 14y ago
    Thank you for your time, enlightened one.
  • efnx 14y ago
    What it comes down to is that Haskell's type system eliminates whole categories of bugs because of the language. Having the correct way to use the language outside of the language itself, as an addition, in the case of Python or Ruby or (insert interpreted language here) makes for lots of extra debugging time.
    • pekk 14y ago
      When you use a programming language, you use its ecosystem. Haskell has its own tools and norms outside "the language itself" which I am obligated to take advantage of. If I develop software in Haskell, but completely ignore these tools, and make complaints which have DIRECTLY to do with my non-use of available facilities, I do not then have the right to say that Haskell is broken and objectively worse than language X. It does not follow. Writing unit tests is not hard. Nor is it rare or exceptional. Wrestling Haskell's type system is not necessarily easy. Overall, making programs do the right thing is a big problem in any language, including Haskell, and one hopes that any system of significant size is being tested properly whether it uses a static type system or not. The use of a type system is not in itself an objective slam dunk for Haskell over Python or anything else.
      • gtani 14y ago
        Have you coded in haskell? Really, the great-grandfather post that provoked this wasn't an attack on python, it's pointing out a difference between the type systems in ML, haskell, scala, and maybe typed racket, of the non-dependently type languages vs. all others.
      • Ixiaus 14y ago
        I use Python + Pyramid daily; and I love it. However, I love Haskell more. Yesod/Snap/Happstack have quite a ways to go before they are on-par community and feature wise with Pyramid/Django/Rails/etc... but it's mature enough for production use. With a little extra learning curve; it beats the pants off of Python + Pyramid + unit tests and lots of extra debugging time.
  • chongli 14y ago
    In other words: do the job that the compiler would have done for you if you'd been using Haskell!
    • pekk 14y ago
      When you are spending a significant amount of time telling the type system which assertions to make about your program, the compiler is not doing that work for you. I am concerned that it is forbidden even to question Haskell advocacy around here, even where it extends into pretty bald bashing of other languages.
      • tikhonj 14y ago
        Which is fine, because in Haskell you aren't spending all that much time telling the compiler which assertions to make. The compiler can infer essentially all the types in your program. In fact, this is so useful that new versions of GHC are going to support "type holes". If you don't know what type you need in any particular part of the code, you can just write a _ there, and the compiler will tell you what type goes there! So really, you're not spending time telling the type system which assertions to make--the type system is telling you what you need. This is going to enable a much more interactive development style that leverages the power of the compiler to help you write your program. I think a more interactive development system is the future, and this is a good (albeit fairly small) step in that direction. Also, as an interesting aside, the type inference can actually make your code more expressive. In both Haskell and Python, you could write a function called toString that takes an argument and returns it as a string. However, the really cool thing is that in Haskell you can write the opposite function--fromString. This function takes a string and returns a value. The real beauty is that the compiler can infer what type you need and choose the appropriate parser; in Python (or, really, virtually any other language), you would have to specify whether you want an int or a double or a Foo or a Bar explicitly. So: the types are inferred for you, you can use these inferred types to help you write your program and they actually make the code more expressive. I think it's a pretty good deal.
        • eru 14y ago
  • DanWaterworth 14y ago
    Types and tests give completely different assurances. Tests give you assurance that a particular code path works at least some of the time. Types give you assurance that an invariant is true all of the time.
• gnuvince 14y ago
  Really hoping to see that application, I've been meaning to pick up Yesod, but school and all that are getting in the way.
• laureny 14y ago
  > In Python I run into a lot of programmer related bugs that Haskell's rigid type system prevents. Isn't your productivity gain coming from using a statically typed language rather than Haskell specifically? It feels like any statically typed language is a leg up from Python :)
  • freyrs3 14y ago
    > Isn't your productivity gain coming from using a statically typed language rather than Haskell specifically I think it's a bit more than that, Haskell has a much more sophisticated type system than quite a few of the popular statically typed langauges ( C, Java, C# ). Static typing is only the start, to be really useful we need modern type inference methods and a concise way of expressing generics. Both Scala and Haskell do this very well.
  • mightybyte 14y ago
    Purity is a big factor too, and Haskell is the only pure language I know of that is mature enough for production use.
  • codewright 14y ago
    Are we still spreading that canard where type errors are somehow some kind of bugbear in Python? It's not a profound part of writing code in Python for anybody that's spent more than a few weeks with it.
    • mercurial 14y ago
      A profound part? Maybe not. However, I noticed yesterday that a provisioning tool I wrote was blowing because I was assigning by mistake an empty string coming from a CSV instead of a None value to an integer field in an sqlalchemy model. That's a bug a static type system would have found.
    • donri 14y ago
      Almost every exception a Python program ever throws is or can be made a type error (or otherwise statically caught) in Haskell and similar languages. A type error is not the same thing as a TypeError.
• minikomi 14y ago
  I would love to see a "from nothing to web app" style piece of writing on this. It sounds intriguing. Blog, paid videocast, book, set of tutorials.. If you're interested in doing one, perhaps as a noob I could provide some "that's hard to grasp" style feedback and collaboration (mail in profile hinthint).
  • melling 14y ago
    Kickstarter project? Chris Coyier did a great set for his site redesign, for example. http://www.kickstarter.com/projects/150422311/screencasting-a-complete-redesign?ref=search http://www.kickstarter.com/projects/150422311/screencasting-...
  • s_kilk 14y ago
    I've been toying with the idea of writing a Yesod equivalent for the excellent Rails Tutorial by Michael Hartl. I need to get a bit more comfortable with Yesod first however, so it may take a while. I do think that is what the Yesod world is in most need of right now, a "get stuck in" tutorial that takes the reader from zero to a substantial web app.
    • FPguy 14y ago
      If you decide to do so, you are welcome to post tutorials on the School of Haskell.
  • Ixiaus 14y ago
    Great idea; if I find the time I'll think about putting something together. Good to know there is interest in this.
    • minikomi 14y ago
      Great! Something along the lines of the angular.js videocasts which popped up a few days ago would be great. Small digestible pieces which fit together like legos in your mind.. :)
• deleted 14y ago
  [deleted]
• FPguy 14y ago
  Thanks. In fact we used Haskell + Yesod + Fay to build the School of Haskell itself.