[Haskell-beginners] Help - I'm completely lost with building a really simple app with Snap and Groundhog

[amindfv at gmail.com]

El Jun 20, 2015, a las 16:50, Peter Harpending <peter at harpending.org> escribió:

> On Sat, Jun 20, 2015 at 09:54:27PM +0200, Matthias Beyer wrote:
>> I am learning Haskell by trying to implement a really simple CRUD like
>> web app with Snap and Groundhog - and I'm completely lost, cannot get
>> it to work.
> 
> Since you seem to know what all of those things are, I'm going to assume
> you have some background in imperative programming. This assumption is
> backed by your GitHub history.
> 
> I'm guessing, after the initial few languages, with most programming
> languages you've encountered thus far, you can learn a new one in a week
> or two.
> 
> Haskell isn't like other languages. It requires a fundamentally
> different manner of thinking about your program. It's like learning to
> program all over again. It is worth it, I promise.
> 
> As for learning Haskell, Chris Allen's tutorial has links to resources
> covering everything under the sun:
> <https://github.com/bitemyapp/learnhaskell>.
> 
> Now, regarding your actual question: what's wrong with the code you have
> posted?
> 
> 1. First of all, your dependencies are way too strict in your cabal
>   file. In fact, most of them conflict. I couldn't even run `cabal
>   install`.
> 
>   If you want to make sure the packages play together nicely, you
>   should use Stackage <http://www.stackage.org>.
> 
> 2. Nobody uses old versions of base anymore. You don't need that
>   old-base stuff.
> 
> 3. Your cabal file needs a default-language field.
> 
> 4. Snap is a bit labor-intensive. Yesod <http://www.yesodweb.com> is
>   much more well-suited for non-trivial web applications.
> 

[[citation needed]]
Snap is used for lots of large production sites, and I don't think anyone would claim it's more complex for a beginner.
Not starting a flamewar, just disputung that one is worse.


> Once I cleaned up the cabal file, I was able to get the standard Hello,
> World Snap application running on localhost.
> 
> I forked your repository on GitHub. You can see the changes I made here:
> <https://github.com/matthiasbeyer/rate.hs/compare/master...pharpend:master>. Note
> that I am using GHC 7.10, which is the latest version. You might be on
> an old version of GHC, in which case, you should do the following:
> 
>    rm cabal.config
>    cabal install
>    cabal freeze
> 
> To run the application, I just used `cabal run`.
> 
> Peter Harpending
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