“Yesod devel”在发展中失败 [英] "Yesod devel" fails with fromJust in devel.hs

问题描述

当我运行yesod devel时，它会显示devel.hs：Maybe.fromJust：Nothing

  yesod init＃已创建一个项目bbbb 
 ... 
 cabal install&& yesod devel 
 ... 
注册bbbb-0.0.0 ... 
启动开发服务器。 .. 
开始devel应用程序
 devel.hs：Maybe.fromJust：Nothing 
  

Web服务器没有监听端口（我无法在浏览器中打开网站）

有人知道如何解决这个问题吗？

我的环境：

• yesod-0.9.4.1


• Glorious Glasgow Haskell编译系统，版本7.0.3
  
• Mac OS X 10.6.8
  

这里是dist / devel.hs，其中创建了yesod init：

  { - ＃LANGUAGE PackageImports＃ - } 
导入bbbb应用程序（withDevelAppPort）
导入Data.Dynamic（fromDynamic）
导入Network.Wai.Handler.Warp 
（runSettings，defaultSettings，settings Port，settingsHost）
 import Data.Maybe（fromJust）
 import Control.Concurrent（forkIO）
 import System.Directory（doesFileExist，removeFile）
 import System.Exit（exitSuccess） 
 import Control.Concurrent（threadDelay）
 $ b $ main :: IO（）
 main = do 
 putStrLn启动devel应用程序
 wdap<  - （回报。来自Just。 fromDynamic）withDevelAppPort 
 forkIO。 wdap $ \（port，app） - > runSettings defaultSettings 
 {settingsPort = port 
，settingsHost =0.0.0.0
} app 
 loop 
 
 loop :: IO（）
 loop = do 
 threadDelay 100000 
e < -  doesFileExistdist / devel-terminate
 if e then terminateDevel else loop 
 
 terminateDevel :: IO（）
 terminateDevel = exitSuccess 
  

我上传bbbb目录中的所有文件，Application.hs是
https://github.com/suztomo/LanguageStudy/ blob / master / Haskell / Yesod / bbbb / Application.hs 。 解决方案

检查你的cabal文件是否使用了yesod-default 0.5。

When I run "yesod devel" it says "devel.hs: Maybe.fromJust: Nothing

yesod init # created a project bbbb
...
cabal install && yesod devel
...
Registering bbbb-0.0.0...
Starting development server...
Starting devel application
devel.hs: Maybe.fromJust: Nothing

And the web server is not listening the port (I cannot open the site in my browser)

Does anyone know how to fix this?

My environment:

• yesod-0.9.4.1
• The Glorious Glasgow Haskell Compilation System, version 7.0.3
• Mac OS X 10.6.8

Here is dist/devel.hs, which "yesod init" created:

{-# LANGUAGE PackageImports #-}
import "bbbb" Application (withDevelAppPort)
import Data.Dynamic (fromDynamic)
import Network.Wai.Handler.Warp
    (runSettings, defaultSettings, settingsPort, settingsHost)
import Data.Maybe (fromJust)
import Control.Concurrent (forkIO)
import System.Directory (doesFileExist, removeFile)
import System.Exit (exitSuccess)
import Control.Concurrent (threadDelay)

main :: IO ()
main = do
  putStrLn "Starting devel application"
  wdap <- (return . fromJust . fromDynamic) withDevelAppPort
  forkIO . wdap $ \(port, app) -> runSettings defaultSettings
    { settingsPort = port
    , settingsHost = "0.0.0.0"
    } app
  loop

loop :: IO ()
loop = do
  threadDelay 100000
  e <- doesFileExist "dist/devel-terminate"
  if e then terminateDevel else loop

terminateDevel :: IO ()
terminateDevel = exitSuccess

I uploaded all files in bbbb directory and Application.hs is https://github.com/suztomo/LanguageStudy/blob/master/Haskell/Yesod/bbbb/Application.hs .

解决方案

A shot in the dark answer: check in your cabal file that you're using yesod-default 0.5.

这篇关于“Yesod devel”在发展中失败的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！