Ask HN: Snap v Nitrogen v Lift v Compojure | Hacker News Reader

Ask HN: Snap v Nitrogen v Lift v Compojure

25 pointsacconrad14 comments

I feel like this is the new "Rails v Django" discussion, but I'm really new to functional programming languages. My only experience is a bit of PLT Scheme/Racket and OCaml in college, but I want to get back into it via web development. Everyone seems to lean towards Haskell, Erlang, Clojure and Scala over here so I'm curious to hear your experiences with their most popular web frameworks. Are they as analogous as a Rails v Django comparison? The only thing I can comment on is Lift appears convincing with their users list, but Scala seems like it would be a poor way to learn functional programming because it's not purely functional.

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Of the listed frameworks I only have (limited) experience with compojure, but here is my advice. I love functional programming, but i think that we've over-hyped it a little. As you know(i hope), there are no silver bullets. I wouldn't worry about a language being impure, purity is over hyped as well, clojure is also impure. What I used to do with clojure was to take a bunch of components(compojure, sandbar, hiccup etc.) and glue them together to make an app. I haven't been following the clojure scene for a while, but i believe thats the idiomatic way to write web apps, not the full stack style of rails or django, where you just fill in the blanks.

I wrote the majority of my startup's code in Clojure using compojure et al. and that is indeed the way you end up doing it. These pieces that you use together, however, didn't require any glue for me. Like all functional programming, you use the pieces that you need in your application. In general, compojure and hiccup will take care of just about everything you need. If someone wanted a full service rails-like package, though, conjure can give that to you.

The benefit of not using a one sized fits all kind of framework, is that you have immense flexibility. Want to write your templates in more of a PHP style? Use string template instead of hiccup. Want to do it like JQuery on the server, use enlive. You have tons of options.

That being said, it's definitely new territory and not for the faint hearted. You will have to feel your way around a bit, but at the same time there is an extremely active and helpful community. The guy who works on compojure, for example, often responds in a matter of hours.

Now having written a fairly sizable app in clojure, I'll happily say it's by far the best experience I've had writing a web app. Once past the rough edges, there's just something to be said for generating your html in manipulable clojure structures that can be mapped over and all sorts of other fun things.

I've been using Clojure and Compojure this weekend. So far it's a big thumbs down. Documentation is terrible. Pretty sure I just killed a weekend on an over-hyped development style with an under documented ecosystem.

Oh, and good luck finding a tutorial for any recent version of Compojure or any of the components. Seems they rearranged all the code and broke it out into several different projects, which makes all the pre-0.4 tutorials useless.

So far it looks like the most helpful resources are: http://vimeo.com/8356990 http://stackoverflow.com/questions/3122749/good-current-docu... and http://cleancode.se/2010/08/30/getting-started-with-compojur...

Piecing together the documentation can certainly be painful, especially if you are doing things that don't mesh with the norm (for example last time I was refreshing myself on enlive the tutorials for that had switched to mustache, while I prefer compojure) making things entertaining until you get back into the groove.

However for me I love the power that comes with the fact I can piece together the parts I want easily after some initial experimentation, as they are all built to be independent of each other. Makes the workflow more fluid.

Though if I were to even want more of an "all in one box" solution I would be more prone to use Scala + Lift right now.

It seems like there's an opportunity here and I'll see what I can do to piece something together to help folks get started. I will say that aside from the pieces being split apart, compojure/ring/hiccup haven't really changed all that much since I started using them about 5-6 months ago. The main difference being that instead of compojure being a one size fits all framework, it's now in pieces. That should generally just mean a couple extra includes, though.

If you have any specific questions, I'd be happy to try and answer them. Also I'd love to get a sense for what you think is missing. I've recently started on some ideas for creating a more solid starting point for people, basically a simple framework for rapidly prototyping websites in clojure. The more I can get a sense for what needs to be in there, the better it'll be.

There is a growing community with quite a bit of support surrounding scala particularly for web development. Lift is well documented and in production at Foursquare which is vote of confidence. The Guardian is also switching to scala as described here http://www.infoq.com/articles/guardian_scala. Plus Twitter, Yammer and a bunch of others are also using scala for "web related" development.

Overall I think as it exists now Scala has the best community particularly around web development. Much like the Django v Rails debate try them out and see what you like.

I know personally scala is second on my list behind Ruby.

There's definitely some subjectivity and it comes down to what you want from a language and framework. I think Haskell is the best way to learn functional programming because it's pure, has a powerful type system and helpful community, and it's easy to use it to replace shell scripts. One of the things that really bothers me about JVM based languages is the startup time that makes it painful to use them as shell scripts, but if you're just writing a web application this might not be an issue.

If you decide to go with Haskell then you need to decide what kind of framework you want. I started with Snap and it I enjoyed using it but it doesn't have the high level functionality that Rails or Django do. I'm now using Yesod and it's great. It seems very Haskelly to me and the high level functionality means I don't have to write my own authentication system and persistence layer.

If you're having problems with JVM startup time, there are things like Nailgun that can solve that for you: http://www.martiansoftware.com/nailgun/

I see what you mean about Yesod, it seems to play to the strengths of Haskell quite well from my quick glance.

http://github.com/icylisper/jark

Project Website: http://icylisper.in/jark/

That looks interesting, but at least for the near future solutions like that aren't good for things you want other people to run without having to do a lot of work. That said, I'll definitely look into using that as I learn Clojure.

Regarding Clojure, while compojure is popular, a compojure centric view of web programming is misguided. Compojure is part of a growing ecosystem of libraries built on top of ring[1][2].

Firstly this ecosystem is not analogous to rails or django. The closest is that Compojure is similar to Sinatra i believe.

If you are looking at getting started with web programming in Clojure you need to get familiar with ring (the http abstraction) and look at Compojure and Moustache (routing and handler composition), and Enlive[4] and Hiccup[5] (templating/html generation). Compojure and Moustache are fairly similar, but Enlive and Hiccup are extremely different. A web application will consist of ring plus one of each layer.

As has been mentioned by others in this thread, the depth, breadth and currentness of documentation for these libraries varies. David Nolen has a great tutorial for enlive[6] that i would encourage anyone looking at these libs to work through. Enlive is one of the most compelling aspects of the clojure web ecosystem at present.

These libraries provide the core pieces you would expect to see in any web framework, but a lot of the smaller details are missing. Of note there is no ORM for clojure (for obvious reasons) - If you are looking for a good SQL abstraction you should look at ClojureQL[7] - and aspects such as form generation, validation and processing is still in early days.

My day job has me building web apps with Django. I wouldnt suggest that my coworkers and I jump to clojure / ring et al yet. The breadth of libraries and out of the box stuff in django is still a huge advantage for the day to day rapid web site / web app development, however clojure's story is improving rapidly and i think that the functional model is a particularly good fit for web applications.

I cannot compare clojure's story with the other languages and frameworks mentioned.

  [1] https://github.com/mmcgrana/ring/ 
  [2] This is true of compojure 0.4 and newer. compojure existed prior to ring (with hiccup as part of it).
  [3] https://github.com/cgrand/moustache
  [4] https://github.com/cgrand/enlive
  [5] https://github.com/weavejester/hiccup
  [6] There is a link in the enlive readme
  [7] https://github.com/LauJensen/clojureql/

RE: Nitrogen. I've started using an Erlang RESTful HTTP toolkit called Webmachine (http://webmachine.basho.com/) paired with an Erlang-based distributed key-value store called Riak (http://wiki.basho.com/) and I am very pleased with the ease of using these libraries. However, I can't offer you a comparison with other functional languages as I only have experience with Erlang.

I'm starting an extended and thorough series of technical articles regarding deploying Webmachine and Riak on Amazon Web Services on my personal website. Over the next week feel free to follow the articles and see what you think of Webmachine/Riak!

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