Update examples

.gitignore

@@ -0,0 +1,2 @@
+dist-newstyle/
+.stack-work/

cabal.project

@@ -0,0 +1,4 @@
+packages: .
+
+package network-multicast
+  flags: +examples

examples/receiver.hs

@@ -2,12 +2,11 @@ import Network.Socket (withSocketsDo)
 import qualified Data.ByteString.Char8 as C
 import Network.Socket.ByteString (recvFrom)
 import Network.Multicast
+import Control.Monad (forever)
 
 main :: IO ()
 main = withSocketsDo $ do
     sock <- multicastReceiver "224.0.0.99" 9999
-    let loop = do
+    forever $ do
         (msg, addr) <- recvFrom sock 1024
         putStrLn $ "Recv [" ++ show addr ++ "]: " ++ C.unpack msg
-        loop
-    loop

examples/sender.hs

@@ -5,14 +5,13 @@ import Network.Multicast
 
 import Data.Time.Clock (getCurrentTime)
 import Control.Concurrent (threadDelay)
+import Control.Monad (forever)
 
 main :: IO ()
 main = withSocketsDo $ do
     (sock, addr) <- multicastSender "224.0.0.99" 9999
-    let loop = do
+    forever $ do
         msg <- fmap show getCurrentTime
         sendTo sock (C.pack msg) addr
         putStrLn $ "Send [" ++ show addr ++ "]: " ++ msg
-        threadDelay 100000
-        loop
-    loop
+        threadDelay 1000000

network-multicast.cabal

@@ -1,3 +1,4 @@
+cabal-version:      2.0
 name:               network-multicast
 version:            0.3.2
 copyright:          2008-2019 Audrey Tang
@@ -11,17 +12,42 @@ description:        The "Network.Multicast" module is for sending
 stability:          experimental
 build-type:         Simple
 category:           Network
-cabal-version:      >= 1.8
 extra-source-files: examples/sender.hs examples/receiver.hs ChangeLog
 
+flag examples
+  description:
+    Build executable examples.
+  default:
+    False
+  manual:
+    True
+
 library
-    extensions:         ForeignFunctionInterface, CPP, FlexibleInstances
+    default-extensions:         ForeignFunctionInterface, CPP, FlexibleInstances
     exposed-modules:    Network.Multicast
     build-depends:      base >= 4 && < 5, network, network-bsd
     hs-source-dirs:     src
     if os(win32)
         extra-libraries: ws2_32
 
+executable receiver
+  main-is: receiver.hs
+  hs-source-dirs: examples
+  default-language: Haskell2010
+  if !flag(examples)
+    buildable: False
+  else
+    build-depends: base, bytestring, network, network-multicast
+
+executable sender
+  main-is: sender.hs
+  hs-source-dirs: examples
+  default-language: Haskell2010
+  if !flag(examples)
+    buildable: False
+  else
+    build-depends: base, bytestring, network, network-multicast, time
+
 source-repository head
   type:     git
   location: http://github.com/audreyt/network-multicast