Bird

A sinatra-ish web framework written in haskell, riding on top of Hack.

Why?

Sinatra has a beautiful, simple, elegant syntax, but it's essentially an attempt to bring pattern matching to a language never intended for pattern matching. Why not attempt something similar in a language with not just beautiful pattern matching, but with all the declarative bells and whistles: lazy evaluation, first-class functions, currying, polymorphism?

Install

λ cabal update && cabal install bird

Note: make sure $HOME/.cabal/bin is in your PATH.

Create an app

λ bird hatch StarWars
  A fresh bird app has been created in StarWars.

Compile your app

λ cd StarWars
λ bird nest 
  [1 of 2] Compiling StarWars           ( StarWars.hs, StarWars.o )
  [2 of 2] Compiling Main               ( Main.hs, Main.o )
  Linking Main ...
λ

Start your app (runs on port 3000)

λ bird fly
  A bird was just spotted in flight at http://localhost:3000

Try it out

λ curl http://localhost:3000
  Hello, Bird!

Improvise!

-- StarWars.bird.hs
import Data.String.Utils (join)

get ["droids"] = do
  body "These aren't the droids you're looking for. Move along."
  status 404

post ["jedi"] = do
  name <- param "name"
  teacher <- param "teacher"
  case teacher of 
    Just "Yoda" -> body "The force is strong with this one!"      >> status 201
    _           -> body "Sorry. The force is not with this one."  >> status 400 


get ("force":xs) = do
  body $ "May the force be with you " ++ (join ", " xs) ++ "!"

get [] = do
  name <- param "name"
  log "I'm about to greet a Jedi. Teehee!"
  body $ "Greetings, " ++ (maybe "Jedi!" id name)

Now recompile your app and start it flying:

λ bird nest
λ bird fly &

λ curl -i http://localhost:3000/force/Han/Chewie

    HTTP/1.1 200 OK
    Connection: close
    Content-Type: text/html
    Date: Sat, 31 Jul 2010 14:07:17 GMT
    Server: Happstack/0.5.0.2

    May the force be with you Han, Chewie!


λ curl -i -X POST http://localhost:3000/jedi -d name=Luke -d teacher=Yoda
    
    HTTP/1.1 201 Created
    Connection: close
    Content-Type: text/html
    Date: Sat, 21 Aug 2010 21:38:11 GMT
    Server: Happstack/0.5.0.2

    The force is strong with this one!


λ curl -i http://localhost:3000/droids

    HTTP/1.1 404 Not Found
    Connection: close
    Content-Type: text/html
    Date: Sat, 31 Jul 2010 14:08:35 GMT
    Server: Happstack/0.5.0.2

    These aren't the droids you're looking for. Move along.

API

You have four functions to implement: get, post, put, and delete. They each accept a Bird Request.

Inside the function body, you can use the following methods (don't worry, this is a growing list):

param :: String -> Maybe String
-- ex: for the request GET /droids?name=c3po,
--     then `p <- param "name"' would bind the value `Just "c3po"' to the variable "p"

body :: String -> BirdResponder ()
-- takes a string and sets the Http Response body to whatever the string contained.

status :: Integer -> BirdResponder ()
-- takes a number, and sets the HTTP Reponse header "Status" to that number.

mime :: String -> BirdResponder ()
-- sets the mime type to whatever you provide
-- ex: get [] = body "Hello World" >> mime "text/plain"

header :: String -> String -> BirdResponder ()
-- creates/updates a header
-- ex: get [] = body "Hello World" >> header "X-Powered-By" "BIRD!"

log :: String -> BirdResponder ()
-- adds to the log
-- ex: get [] = body "Hello World" >> log "Why did I just greet the world?"

Notes

This project is still in its infancy. Coming features:

• support for multipart forms submissions
• helpers for popular html generation solutions (Hamlet, HStringTemplate, HAXML, BlazeHTML, etc.)
• WAI support
• static asset serving
• support for sending files