Happstack

Happstack (Haskell Application Stack) is a free application server for websites written in the functional programming language Haskell. It integrates handling Web, persistence, XML/XSLT, and templating functionality.^[1]

It makes use of a number of Haskell libraries and systems such as Parsec, Cabal, Template Haskell, and monad transformers ("Your app then is just a set of state transformer functions (in the MACID Monad) that take an event and state as input and that evaluate to a new state, a response, and a (possibly null) set of sideeffects."^[1]) among others.

Relation to HAppS

Happstack is the continuation of the HAppS project.^[2] The project name was changed to highlight the transition to a more open development model and a change in project leadership. The transition was made with the blessing of Alex Jacobson, and the HAppS developers are still involved in the coding.

See also

• Staged event-driven architecture (SEDA)
• Prevayler
• Twisted

References

External links

• Happstack Maintained, current version
• HAppS homepage
• Author of HAppS Alex Jacobson presenting HAppS to the Bay Area Functional Programmers group (video & slides)
• Haskell Application Server - HAppS
• "Case Study: Using Haskell and HAppS for Openomy API v2.0"
• Self-Demoing Cabal Installable HAppS Tutorial