add an example on how to derive client functions for Hackage

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Alp Mestanogullari 2015-04-23 13:07:52 +02:00
parent 6651df574a
commit 29632c4ac2
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servant-examples/LICENSE Normal file
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Copyright (c) 2015, Alp Mestanogullari
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following
disclaimer in the documentation and/or other materials provided
with the distribution.
* Neither the name of Alp Mestanogullari nor the names of other
contributors may be used to endorse or promote products derived
from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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import Distribution.Simple
main = defaultMain

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{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE OverloadedStrings #-}
import Control.Applicative
import Control.Monad
import Control.Monad.IO.Class
import Control.Monad.Trans.Either
import Data.Aeson
import Data.Monoid
import Data.Proxy
import Data.Text (Text)
import GHC.Generics
import Servant.API
import Servant.Client
import qualified Data.Text as T
import qualified Data.Text.IO as T
type HackageAPI =
"users" :> Get '[JSON] [UserSummary]
:<|> "user" :> Capture "username" Username :> Get '[JSON] UserDetailed
:<|> "packages" :> Get '[JSON] [Package]
type Username = Text
data UserSummary = UserSummary
{ summaryUsername :: Username
, summaryUserid :: Int
} deriving (Eq, Show)
instance FromJSON UserSummary where
parseJSON (Object o) =
UserSummary <$> o .: "username"
<*> o .: "userid"
parseJSON _ = mzero
type Group = Text
data UserDetailed = UserDetailed
{ username :: Username
, userid :: Int
, groups :: [Group]
} deriving (Eq, Show, Generic)
instance FromJSON UserDetailed
newtype Package = Package { packageName :: Text }
deriving (Eq, Show, Generic)
instance FromJSON Package
hackageAPI :: Proxy HackageAPI
hackageAPI = Proxy
getUsers :: BaseUrl -> EitherT ServantError IO [UserSummary]
getUser :: Username -> BaseUrl -> EitherT ServantError IO UserDetailed
getPackages :: BaseUrl -> EitherT ServantError IO [Package]
getUsers :<|> getUser :<|> getPackages = client hackageAPI
run :: (BaseUrl -> r) -> r
run f = f (BaseUrl Http "hackage.haskell.org" 80)
main :: IO ()
main = print =<< uselessNumbers
uselessNumbers :: IO (Either ServantError ())
uselessNumbers = runEitherT $ do
users <- run getUsers
liftIO . putStrLn $ show (length users) ++ " users"
user <- liftIO $ do
putStrLn "Enter a valid hackage username"
T.getLine
userDetailed <- run (getUser user)
liftIO . T.putStrLn $ user <> " maintains " <> T.pack (show (length $ groups userDetailed)) <> " packages"
packages <- run getPackages
let monadPackages = filter (isMonadPackage . packageName) packages
liftIO . putStrLn $ show (length monadPackages) ++ " monad packages"
where isMonadPackage = T.isInfixOf "monad"

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name: servant-examples
version: 0.3
synopsis: Example programs for servant
description: Example programs for servant
homepage: http://haskell-servant.github.io/
license: BSD3
license-file: LICENSE
author: Alp Mestanogullari
maintainer: alpmestan@gmail.com
-- copyright:
category: Web
build-type: Simple
-- extra-source-files:
cabal-version: >=1.10
executable hackage
main-is: hackage.hs
-- other-modules:
-- other-extensions:
build-depends:
aeson >= 0.8
, base >=4.7
, either
, servant
, servant-client
, text
, transformers
hs-source-dirs: hackage
default-language: Haskell2010