## Who let you in here?

Relax! I'm here to make your life easier. Has your company ever
switched to using [Slack](https://slack.com), and then you wanted to
write silly Slack bots in Haskell as a way to learn Haskell?

<sup>Really?<sup>Wow<sup>That was a pretty specific question.</sup></sup>

Uh, do you want to be friends? Well let's talk about it later, because right now I have an example for you.

## Show me an example!

Here's a `/jpgto` bot. If you run this program and then tell Slack
about your server (incoming hook and custom slash command) and then
type `/jpgto diplomatico` in one of your channels, you'll get the
image from [http://diplomatico.jpg.to](http://diplomatico.jpg.to). How, you say? _Screen scraping_.

```haskell
import Network.Linklater (say, slash,
                          Command(..), Config(..), Icon(..), Message(..), User(..))

urlParser :: Parser B.ByteString
urlParser = p
  where
    p = garbage *> url
    garbage = string "src=\"" <|> (P.take 1 *> garbage)
    url = takeTill (== _quotedbl)

urlFor :: Text -> IO Text
urlFor search = do
  r <- get (T.unpack $ F.format "http://{}.jpg.to/" [search])
  (return . handle . parse urlParser . strictly) (r ^. responseBody)
  where
    strictly = B.concat . L.toChunks
    handle (Fail i ctxs s) = error (show (i, ctxs, s))
    handle (Partial f) = handle (f "")
    handle (Done _ r) = toText r

jpgto :: Maybe Command -> Application
jpgto (Just (Command (User user) channel text)) req respond = do
  url <- urlFor (maybe "spolsky" id text)
  say (Message channel (response url) (EmojiIcon "gift")) config
  (respond . responseLBS status200 headers) ""
  where
    response url = F.format "@{} {}" (user, url)
    config = Config token "trello.slack.com"
    headers = [("Content-Type", "text/plain")]

main :: IO ()
main = do
  let port = 80
  putStrLn (F.format "+ Listening on port {}" [port])
  run port (slash jpgto)
  return ()
```

For the full example (since this one is missing a ton of imports), see
the `examples/` directory on GitHub.

Now! `/jpgto corgi`:

![jpgtobot in action](corgi.jpg)

So easy. Much fast.

## Features

* Uses `Text` everywhere so you can send your slash commands crazy Unicode characters all day long.
* Lovely documentation.
* Battle-tested.


## Contributors

* [Hao Lian](https://hao.codes), author
* [Ian Henry](https://ianthehenry.com), design review and _future contributor_???
* *Shields* (the Grizzly Bear album), which I listened all the way through for the first time while I was writing this ★★★★