Web development: Haskell or Scheme

Question

I would like to to choose one of these languages for building web applications. I'm not interested in framework per se, but have the following needs:

• Rapid development.
• Easy to scale.
• Strong community for the web.
• Quick and easy to deploy.

I'm very familiar with Haskell, and have some familiarity with scheme (in particular PLT). Scheme appeals to me as good candidate for web development due to it's simple syntax which is homogenous across libraries. I state this despite my subjective opinion that Haskell is a 'cleaner' language.

Haskell web apps seem to require learning and building a patchwork of different combinator libraries. On the plus side, I realise this can be quite expressive, although I'd prefer to eliminate impedance mismatches where possible.

While scheme-plt looks to be a good fit, I can find but one example of it being used in the "real world". Haskell doesn't seem to fair too much better here, but there seems to be a bigger community behind the web side.

Please help me make up my mind. For the most part I'm interested in real-world use cases.

Answer 1

Sounds like you want people to make the case for the various languages and toolchains for you. Well, here's what I know about Haskell -- there's a lot of people, tools and experience to help you out:

• 150+ support Web-only libraries and components on Hackage
• > 2000 libraries and tools for Haskell available via "cabal install"
• A big community online -- with lots of web users and support.
• A reasonable community around the happstack framework, including commercial users like Patch-Tag and DB.
• Hot new web frameworks like Snap
• Great end-user apps like Gitit.
• A haskell-for-the-web mailing list community.
• Good support for client-side JS via embedded DSLs.
• Active efforts to provide documented, world-class performance at all levels: network scalability, templating libraries and HTTP layers.
• Good documentation for database use.
• A bigger StackOverflow community (~1000 questions v 400 questions for scheme).
• A single installer for the base system, making your apps easy to deploy.

I think there's no choice, really.

Answer 2

Hi Robert,

[Note: We have renamed "PLT Scheme" to "Racket"; I will refer to it as that.]

"Rapid development."

I find Racket great for rapid development. If you follow the Continue tutorial on using Racket for Web, I think you will as well. You can start prototyping your application without ever saving a file, it's easy to integrate the many packages on PLaneT, and macros remove the burden of ever writing boiler-plate more than once.

"Easy to scale."

I've done a lot of research into scaling Web applications written in Racket. Racket Web applications can use stateful continuations (recorded in the server's RAM) or stateless (recorded in a serializable format and stored by users or databases/etc) or any combination of the two. A brief summary of these distinctions is described in the documentation. For each regime there are an assortment of ways of dealing with scale, such as stateful continuation management policies and stateless stuffers.

I've put a lot of thought into making the defaults scale well, but also easy enough to change for your circumstances.

On the less Web-specific front, we have native support for trendy scalable databases like MongoDB and memcached.

"Strong community for the web."

Apart from usage of our software in education, it seems we are most often deployed on the Web. If you scan through PLaneT you'll see a preponderance of Web-related libraries. I'm not sure of another metric for you.

"Quick and easy to deploy."

I think the rapid development point speaks to this. If you have other questions related to deployment, I'm happy to answer.

"I can find but one example of it being used in the 'real world'."

The guys at Untyped have a few products using it. I've written two commercial sites and at least four other reasonably large community sites. We know of a dozen or so contractors building applications using it. There are a few startups I've talked to that are using it as well. There's no point pretending we're as common as Python or Ruby, etc, but we're not purely academic or theoretical either.

If you have any other questions, feel free to email me directly or the mailing list, so others in our community can more easily benefit from the discussion. Happy hacking!