haskell - 找不到模块 `Yesod'

Question

我有以下代码:

{-# LANGUAGE TypeFamilies, QuasiQuotes, MultiParamTypeClasses,
             TemplateHaskell, OverloadedStrings #-}

module Simple where
import Yesod
data HelloWorld = HelloWorld

mkYesod "HelloWorld" [parseRoutes|
/ HomeR GET
|]

instance Yesod HelloWorld

getHomeR = defaultLayout [whamlet|Hello World!|]

withHelloWorld  f = toWaiApp HelloWorld >>= f

main = warpDebug 3000 HelloWorld

如果在GHCI中运行，则运行正常:

Ok, modules loaded: Simple.
*Simple> main
Application launched, listening on port 3000

但是如果运行它:

wai-handler-devel 3000 Simple withHelloWorld

控制台报错:

pshuvaev@pshuvaev-K73SV:~/works/haskell/yesod/SimpleSite$ wai-handler-devel 3000 Simple.hs withHelloWorld
Attempting to interpret your app...
Compile failed: 

Could not find module `Yesod'
Use -v to see a list of the files searched for.

可能是什么问题？ Yesod 已设置，并显示在 ghc-pkg list 的输出中。

Answer 1

在 Unix 系统上删除 ~/.ghc 目录并运行:

ghc-pkg --global recache

在 Windows 系统上(仅建议)删除 C:\Users\USERNAME\AppData\Roaming\ghc 并从命令行重新缓存(以管理员身份):

ghc-pkg --global recache

不确定Windows!请检查!