Could not find module `Yesod'

Question

I have the following code:

{-# 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

If run it in GHCI, it runs normally:

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

But if run it as:

wai-handler-devel 3000 Simple withHelloWorld

the console reports an error:

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.

What could be the problem? Yesod is set and it displays in the output of ghc-pkg list.

I'm not familiar with `wai-handler-devel` does it look at the local project's cabal file? — asm, Jan 29 '13 at 21:01
I do not have cabal file.. In the directory is only one file - Simple.hs. With runhaskell I try to run later. But on different, just installed operating system (Ubuntu 12.04) and the just installed haskell-platform and yesod this error does not occur. — IPShuvaev, Jan 30 '13 at 09:15
if I run runhaskell, it works fine: `pshuvaev@pshuvaev-K73SV:~/works/haskell/yesod/SimpleSite$ runhaskell Simple.hs Application launched, listening on port 3000` — IPShuvaev, Jan 30 '13 at 15:21

score 2 · Answer 1 · edited Aug 23 '15 at 14:13

2

On Unix systems remove ~/.ghc directory and run:

ghc-pkg --global recache

On Windows systems (just suggestion) remove C:\Users\USERNAME\AppData\Roaming\ghc and also recache from the command line (as Admin):

ghc-pkg --global recache

Not sure about Windows! Please check!

edited Aug 23 '15 at 14:13

Jezen Thomas

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answered Mar 14 '14 at 21:06

crow16384

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Could not find module `Yesod'

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