I've written a simple Hello World application for (Warp) on (Wai). It works fine in Ubuntu Linux, as do more complicated apps. But I can't even get this Hello World app to run in Windows. I'm using Haskell Platform (installation file 2012.2.0.0) on Windows 7 Home Premium SP1 32-bit.
This is the code (which works in Linux):
{-# LANGUAGE OverloadedStrings #-}
import Network
import Network.Wai
import Network.HTTP.Types (status200)
import Network.Wai.Handler.Warp (run)
-------------------------------------------------------------------------------
application = \_-> return $ responseLBS status200 [("Content-Type", "text/plain")]
"Hello World"
main = withSocketsDo $ do run 3000 application
These are the GHCI messages upon loading the code, and running (main):
Prelude> :l wai_hello_world.hs
[1 of 1] Compiling Main ( wai_hello_world.hs, interpreted )
Ok, modules loaded: Main.
*Main> main
Loading package bytestring-0.9.2.1 ... linking ... done.
Loading package [ **edited**: blah blah blah - other packages - removed for readability]
Loading package warp-1.3.2 ... linking ... done.
After loading the code, the web server does not appear to be running.
I think I might be running into some common gotcha - if so please let me know.
Thanks in advance for all feedback.
(Update: as noted in an answer below, these errors are solely due to the Ctrl-C action, killing the runtime, and not part of the unexpected behaviour of Wai/Warp in the question.)
If I hit Ctrl-C a few times to break out, I get these messages, or some variety of them:
NIenttweorrrku.pStoecdk.e t.ace*Main> p: failed (No error) user error (accept: can't perform accept on socket ((AF_INET,Stream,0)) in status Closed) user error (accept: can't perform accept on socket ((AF_INET,Stream,0)) in status Closed) *Main> *Main> user error (accept: can't perform accept on socket ((AF_INE,:Sream,0)) in status Closed) q Leaving GHCi.
You probably need to use withSocketsDo.