Monday, November 14, 2011

ANN: happstack-lite - a friendly introduction to Happstack

Happstack is a powerful Haskell web framework with a rich API that has
evolved over the last 7 years to meet the needs of real world web

Unfortunately a rich and flexible API can also be daunting when all
you need is something simple. What many people don't realize is that
inside Happstack lives a very simple and easy to use web framework.

I am pleased to announce a new member of the Happstack family:


happstack-lite is minimal version of Happstack that is designed give
you everything you need to get started with web develop in a much
cleaner, easier package. It is an ideal starting point for novice Haskell programmers or developers who are new to the Happstack family.

We have done that by:

 1. collecting the most essential types and functions into a single, well-documented module

 2. giving all the functions simple type signatures. No crazy monad
 transformers, far fewer type classes, etc.

 3. creating a new, small tutorial (less than 2000 words) that shows
 you how to use all the features of happstack-lite.

But, the best part is that happstack-lite is 100% compatible with regular Happstack. If you find you do need some of the extra features that Happstack offers, you can simply import the extra functions and use them. Migrating from happstack-lite to happstack is trivial -- mostly just changing `import Happstack.Lite` to `import Happstack.Server`. So, you are not locked into staying with happstack-lite if you decide you need more. And you can still use the many addon packages such as happstack-hsp or happstack-jmacro if you want.

happstack-lite is not crippled or underpowered. In fact, it offers features and performance on par with other Haskell frameworks while being as simple as possible. If you have ever looked at Happstack in the past and felt it was too complicated -- I would highly encourage to look again. Especially if the last time you looked was prior to Happstack 6.

Check out the tutorial here: happstack-lite.

We would love to hear your feedback and criticisms. Please see the related discussion at:


  1. Thanks for this repackage. I was looking at WAI and Warp just a few days back because the modules looked simple. In the end the better documentation of Happstack won out and I used it instead, but always thinking that this just seems "too complicated" of an interface for what I need. This lite version might be close to what I wish I had found in the first place.