我如何使用wai-handler-devel和一个简单的wai应用程序 [英] How do I use wai-handler-devel with a simple wai application

问题描述

我有使用wai的基本的hello world应用程序设置，并且想使用wai-handler-devel，但我不确定如何处理它，并且无法在wai项目的使用中找到它的任何示例。

  { - ＃LANGUAGE OverloadedStrings＃ - } 
 import Network.Wai 
 import Network.HTTP.Types 
导入Network.Wai.Handler.Warp（运行）
导入Data.ByteString.Lazy.Char8（） - 仅适用于孤儿实例
 
 app :: Application 
 app _ = return $ responseLBS 
 status200 
 [（Content-Type，text / plain）] 
Hello，World！ 
 
 main :: IO（）
 main = do 
 putStrLn $http：// localhost：8080 /
运行8080 app 
  

我需要做些什么才能让wai-handler-devel与基本的wai应用程序一起工作？

注意：
这里有一个修正（ https：//gist.github .com / 1499226 ）如果遇到wai-handler-devel：command not found的问题

解决方案

wai-handler-devel的 Hackage页面表示应该从命令中调用它像这样：

  $ wai-handler-devel< port> My.App.Module myApp 
  

并且您的应用程序的类型必须如下所示：

  myApp ::（应用程序 - > IO（）） - > IO（）
  

在这种情况下，您应该定义 myApp


  myApp ::（Application  - > IO（）） - > IO（）
 myApp处理程序=处理程序应用程序
  

尽管您可能想内联<$ c
$ b $ pre $ my $ myApp ::（应用程序 - > IO（）） - $ c $ app> / code> > IO（）
myApp处理程序=处理程序$ \_ - >返回$ responseLBS
status200
[（Content-Type，text / plain）]
Hello，World！


类型是这样的，所以你可以在启动时进行初始化等等。 C $ C> IO 。我建议您阅读 SmallApp 和 wai-handler-devel的git仓库中的FullApp 示例;后者特别有用，因为它具有显示重载期间代码流的调试输出，并显示如何集成长时间运行的数据库连接。

< FullApp示例中的href =https://github.com/yesodweb/wai/blob/master/wai-handler-devel/run-fullapp.hs =nofollow>运行脚本也显示如何以编程方式使用wai-handler-devel，包括手动指定哈姆雷特模板依赖关系（其中 wai-handler-devel 命令行工具自动确定）。

然后，您应该能够按如下方式重写您的 main ：

  main :: IO（）
 main = do 
 putStrLn $http：// localhost：8080 /
 myApp（run 8080）
  

当然，您可以轻松地将运行函数从< a href =http：//hackage.ha skell.org/package/wai-handler-fastcgirel =nofollow> wai-handler-fastcgi ， wai-handler-scgi 或甚至是 wai-handler -webkit 。

I have the basic "hello world" application setup using wai, and would like to use wai-handler-devel, but am unsure how to go about it and can't find any examples of it in usage on a wai project.

{-# LANGUAGE OverloadedStrings #-}
import Network.Wai
import Network.HTTP.Types
import Network.Wai.Handler.Warp (run)
import Data.ByteString.Lazy.Char8 () -- Just for an orphan instance

app :: Application
app _ = return $ responseLBS
    status200
    [("Content-Type", "text/plain")]
    "Hello, World!"

main :: IO ()
main = do
    putStrLn $ "http://localhost:8080/"
    run 8080 app

What do I need to do to get wai-handler-devel working with a basic wai app?

Note: There is a fix here ( https://gist.github.com/1499226) i f you run into issues with "wai-handler-devel: command not found"

解决方案

wai-handler-devel's Hackage page says that it should be invoked from the command-line like so:

$ wai-handler-devel <port> My.App.Module myApp

and that your application's type must look like this:

myApp :: (Application -> IO ()) -> IO ()

In this case, you should define myApp as follows:

myApp :: (Application -> IO ()) -> IO ()
myApp handler = handler app

although you may want to inline app entirely:

myApp :: (Application -> IO ()) -> IO ()
myApp handler = handler $ \_ -> return $ responseLBS
    status200
    [("Content-Type", "text/plain")]
    "Hello, World!"

The type is like this so that you can do initialisation on start-up and the like in IO. I suggest reading the SmallApp and FullApp examples from wai-handler-devel's git repository; the latter is especially helpful, as it has debug output showing the flow of the code during a reload, and shows how to integrate a long-running database connection.

The run script for the FullApp example also shows how to use wai-handler-devel programmatically, including manually specifying Hamlet template dependencies (which the wai-handler-devel command-line tool determines automatically).

You should then be able to rewrite your main as follows:

main :: IO ()
main = do
    putStrLn $ "http://localhost:8080/"
    myApp (run 8080)

Of course, you could just as easily pass the run function from wai-handler-fastcgi, wai-handler-scgi or even wai-handler-webkit.

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