[Haskell] ANN: ivy-web 0.1

James Deng cnjamesdeng at gmail.com
Mon Sep 19 12:34:05 CEST 2011

Dear all,

I am pleased to announce the first release of ivy-web after learning 
haskell for a year.

Ivy-web is a lightweight web framework, with type safe routes, based on 
invertible-syntax, and i18n support, influenced by Django, Snap and Yesod.

The features of this web framework:


    Type safe routes, specify url-handler mapping in one place. For
    example, we want a url mapping for blog as "/blog/year-month-day" to
    Handler Int Int Int, where year, month and day are integers. We can
    declare as follows:

         data Blog = Blog Int Int Int deriving (Show, Eq, Typeable)
         $(defineIsomorphisms ''Blog)

         instance Handler Blog where

            get b@(Blog y m d) _ = do
                 t <- liftIO getClockTime
                 return $ responseHtml $ trans' "blog" ++ show b ++ show t

             rBlog = blog <$> text "/blog/" *> int <-> int <-> int

    We can reverse this mapping from handler value automatically, thus
    don't need to construct url string manually in code, avoiding url

    ghci>url (Blog 2011 9 19) == "/blog/2011-9-19"


    Simple yet elegant handler via type class.

    class Handler a where
         get, post, put, delete, handle :: a -> Application
         handle a req = case requestMethod req of
             m | m == methodGet -> get a req
               | m == methodPost -> post a req
               | m == methodPut -> put a req
               | m == methodDelete -> delete a req
             otherwise -> unimplemented req


    Flexible template system, utilize exsisting libraries such as
    Blaze-Html and Hastache.


    Easy i18n

         Wraps around i18n library.

  * TODO: Auth system

    Port from snap-auth.

  * TODO: Modular app system like Django

         The current route system support modular routes very well. Need 
works in modular config and data files like static template files.

  * TODO: Persistent library

    Improving the DSH library is my current preference.

The principle of this library is KISS, and "don't reinvent the wheel" by 
reusing existing state-of-the-art libraries.

Hackage: http://hackage.haskell.org/package/ivy-web
Repo: https://github.com/lilac/ivy-web/

For the example code listed above, please refer to 

*James Deng*
department of computer science
school of information science & technology
Sun-yat-sen University, Guangzhou, China
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