moonmaster9000

-- is there a GHC language extension that would
-- let me break up function definitions like this:

f1 some_pattern = expression1
f2 some_other_pattern = expression2

f1 yet_another_pattern = expression3
f2 another_pattern = expression4

--instead of having to group them together like this:

moonmaster9000

get ["echo", word]
  | length word == 4 = body "4 letter word" >> status 403
  | otherwise        = body word

moonmaster9000

{-# LANGUAGE TypeFamilies, QuasiQuotes, TemplateHaskell #-}
import Yesod
data Echo = Echo
mkYesod "Echo" [$parseRoutes|
/echo/#String EchoR GET
|]
instance Yesod Echo where approot _ = ""
getEchoR s 
  | length s == 4 = permissionDenied "Forbidden: 4 letter word"
  | otherwise     = return $ RepPlain $ toContent s

moonmaster9000

import qualified Data.ByteString as B

main :: IO ()
main = do
    td <- newTemplateDirectory' "templates" emptyTemplateState
    quickServer $ templateHandler td defaultReloadHandler $ \ts ->
        route [ ("echo/:s", echoHandler)
              ] <|>
        templateServe ts <|>
        dir "static" (fileServe ".")

moonmaster9000

infixl 9 ==>
f ==> g = g $ f

lee     = Author "Gentry Lee"
clarke  = Author "Arthur C. Clarke"
heinlein= Author "Robert Heinlein"
rama    = Book "Garden of Rama"
catalog = 
  Catalog Map.empty Map.empty ==> 
  associate lee rama          ==> 

moonmaster9000

module Library
  (Author,
    Book,
    AuthorIndex,
    BookIndex,
    Catalogued,
    Catalog,
    addAuthor,
    addBook,
    associate,

moonmaster9000

fac n = [1..] ==> take n ==> foldr (*) 1

moonmaster9000

infixl 9 ==>
f ==> g = g $ f

moonmaster9000

fac n = foldr (*) 1 $ take n $ [1..]

moonmaster9000

clarke = createAuthor "Arthur C. Clarke" ["Garden of Rama"]
lee = createAuthor "Gentry Lee" ["Garden of Rama"]

gardenAuthorsAccordingToClarke = map name $ authors $ head $ books clarke 
  -- ["Arthur C. Clarke"]

gardenAuthorsAccordingToLee = map name $ authors $ head $ books lee
  -- ["Gentry Lee"]