Re: [web-devel] Re: ANNOUNCE: yesod 0.2.0

On Mon, May 24, 2010 at 5:35 PM, Gour wrote:

On Mon, 24 May 2010 15:26:02 +0300

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> "Michael" == wrote:

Hello Michael,

Michael> I'm very happy to announce the release of yesod 0.2.0. Yesod Michael> is a Haskell web framework for type-safe, RESTful web Michael> applications.

Congratulations for new release and enhanced web-site!

Michael> The next feature I'm targeting for Yesod is persistence. If Michael> anyone has any thoughts to share on this topic, please send me Michael> an e-mail.

Do you have any rough idea about deploying RDBMS in Yesod?

Otoh, this release of Yesod is coming along the 1st public release of Snap framework...pretty exciting time for Haskell web development.

However, for someone who is still using Hakyll for his web needs (and I must say: "I like it!"), but may ponder into some Haskell framework in the future, I'd be interested to hear about some comparison between Yesod & Snap as far as features, methodology, target users, ease of deploying etc. are concerned?

I would say that Yesod and Snap are very orthogonal projects. Without offense to the Snap authors, I don't really think Snap is a framework; it's much more low-level than that. As they put it, it's at the level of a Java servlet container. In that sense, it's slightly higher-level than WAI, but far more low-level than Yesod (or turbinado, happstack, etc).

I did some work after the Snap release to actually get Yesod running on top of Snap. Gregory has been very helpful, and will hopefully be releasing a newer version of snap-server that provides the functionality I'm missing. (Basically, Snap processes url-encoded form data, while WAI specifies that the POST body be passed to the application.) If you want a real comparison of where the two differ on things, I guess this will suffice: * Yesod uses the WAI definition of enumerator while Snap uses the iteratee package. The former is much simpler, the latter more powerful. I'd be very interested in a performance comparison of the two, my instinct tells me the former wins. * Snap has Heist, which is an XML based templating system, while Yesod uses Hamlet. However, neither framework is actually tied down to these templating systems. In fact, Snap doesn't even depend on Heist. * Yesod has type-safe URLs, I don't believe Snap has any similar feature. However, as I mentioned already, Snap is lower level than Yesod, so you could easily implement type-safe URLs on top of Snap. * Some design decisions, notably they use a mutable states for modifying request and response values while Yesod uses a Reader for the request, and writer for response headers and actually returns a value for the response body/content type. I'm sure there are many more differences, but the main point is this: these two projects are very different types of frameworks. And I hope and expect that the two projects will have some cross-polinization going forward (in fact, we already have). Michael