Haskell module to convert a Twitter message (tweet) to HTML

TweetHTML.hs

{- |
Module      :  TweetHTML
Description :  Convert a Twitter message (tweet) to HTML
Copyright   :  (c) Brian McKenna
License     :  MIT
-}

module TweetHTML (tweetHTML) where

import Data.Char
import Text.Printf
import Text.ParserCombinators.Parsec

data Markers = Plain | Mention | Hashtag | Link

-- Convert a parsed tweet into HTML

homeURL = "http://twitter.com/"
searchURL = homeURL ++ "?search?q=%23"

toHTML (Hashtag, a) = printf "<a href=\"%s\">#%s</a>" (searchURL ++ a) a
toHTML (Mention, a) = printf "@<a href=\"%s\">%s</a>" (homeURL ++ a) a
toHTML (Link, a) = printf "<a href=\"%s\">%s</a>" a a
toHTML (_, a) = a

tweetHTML tweet = case (parse message "" tweet) of
  Right xs -> concatMap toHTML xs

-- Parse a Twitter message (tweet)

identifier = many1 (alphaNum <|> char '_')
notSpace = satisfy (not . isSpace)

link = do
  protocol <- string "http://"
  location <- many1 notSpace
  return (Link, protocol ++ location)

hashtag = do
  char '#'
  ident <- identifier
  return (Hashtag, ident)

mention = do
  char '@'
  ident <- identifier
  return (Mention, ident)
  
word = do
  word <- many1 notSpace
  return (Plain, word)
  
whitespace = do
  ws <- many1 space
  return (Plain, ws)

message = manyTill (choice [whitespace, link, mention, hashtag, word]) eof

-- Show an example

main = putStrLn $ tweetHTML
       "This is a test #tweet from @puffnfresh http://brianmckenna.org/"