HAppS tutorial2

From HaskellWiki
Revision as of 01:16, 4 February 2008 by Mightybyte (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to: navigation, search

Most of the stuff on this page refers to HAppS or greater. This is the most recent development version at the time of this writing. There is another tutorial for HAppS 0.8.8. Start there to get a background. This page is dedicated to the things that have changed in the newer versions.

Author's Note: This page will be in various states of disrepair for awhile. I'm creating this document as I am learning HAppS, so it may reflect my inaccurate perceptions. Some of the information on this page MAY EVEN BE WRONG. If you know it's wrong, I would be grateful for your help in improving it.

HAppS is a framework for developing Internet services quickly, deploying them easily, scaling them massively, and managing them effortlessly. Web, persistence, mail, DNS and database servers are all built-in so you can focus on app development rather than integrating and babysitting lots of different servers/services (the Haskell type system keeps everything consistent).


The ServerPart is the workhorse of defining HAppS actions. The biggest goal of this document is to provide a useful guide to the ServerPart primitives that are available.


Basic ServerPart Functions

High-level description

The definitions for many of these server part primitives can be found in HAppS-HTTP/src/HAppS/Server/SimpleHTTP.hs. However, there is another set of definitions in AlternativeHTTP.hs in the same directory. There are some subtle differences between the two. Hopefully this section will eventually have a complete description of these differences.

 * dir - match a directory at the front of the URL
 * path - another way to match a URL directory
 * multi - run a list of server parts
 * withData
 * withDataFn
 * anyRequest
 * withRequest
 * applyRequest
 * method
 * ok
 * fileServe
 * toResponse


dir :: String -> [ServerPart m] -> ServerPart m

The first argument is matched to the first directory element in the path URL. If it matches, then the server parts in the second argument are run.


path :: (FromReqURI a, Monad m) => (a -> [ServerPart m]) -> ServerPart m

Similar to `dir` except instead of passing a String and a list of server parts, you pass a function that returns a list of server parts.

Error Codes

 * badRequest
 * unauthorizied
 * notFound
 * seeOther
 * found
 * movedPermanently
 * tempRedirect