轉換Data.RVar.RVar [字符]至[字符]

小集團安裝隨機額外轉換Data.RVar.RVar [字符]至[字符]

Prelude Data.Random.Extras> import Data.Random.Extras 
Prelude Data.Random.Extras> let s = shuffle "somestring" 
Prelude Data.Random.Extras> s 

<interactive>:1:1: 
    No instance for (Show (Data.RVar.RVar [Char])) 
     arising from a use of `print' 
    Possible fix: 
     add an instance declaration for (Show (Data.RVar.RVar [Char])) 
    In a stmt of an interactive GHCi command: print it

我如何轉換Data.RVar.RVar [字符]至[字符]？

更新時間：

我無法導入Data.Random.Source.DevRandom：

Prelude> import Data.Random hiding (shuffle) 
Prelude Data.Random> import Data.Random.Source.DevRandom 

<no location info>: 
    Could not find module `Data.Random.Source.DevRandom': 
     Use -v to see a list of the files searched for.

但是：

[59]: cabal install random-fu 
Resolving dependencies... 
No packages to be installed. All the requested packages are already installed. 
If you want to reinstall anyway then use the --reinstall flag. 
[60]: cabal install random-source 
Resolving dependencies... 
No packages to be installed. All the requested packages are already installed. 
If you want to reinstall anyway then use the --reinstall flag.

更新2：

*Main System.Random> import Data.Random hiding (shuffle) 
*Main System.Random Data.Random> import Data.Random.Source.Std 
*Main System.Random Data.Random Data.Random.Source.Std> import Data.Random.Extras 
*Main System.Random Data.Random Data.Random.Source.Std Data.Random.Extras> let reversed = runRVar (shuffle "somestring") StdRandom 

<interactive>:1:16: 
    Ambiguous type variable `m0' in the constraints: 
     (MonadRandom m0) arising from a use of `runRVar' 
         at <interactive>:1:16-22 
     (Monad m0) arising from a use of `runRVar' at <interactive>:1:16-22 
    Probable fix: add a type signature that fixes these type variable(s) 
    In the expression: runRVar (shuffle "somestring") StdRandom 
    In an equation for `reversed': 
     reversed = runRVar (shuffle "somestring") StdRandom

來源

2012-10-29 demas

'Data.Random.Source.DevRandom'也包含在'隨機extra'包（'[11 9]編譯Data.Random.Source.DevRandom（src/Data/Random/Source/DevRandom.hs，dist/build/Data/Random/Source/DevRandom.o）'）。 – leftaroundabout

也許是隨機附加的？我也是這樣安裝的。 – demas

這裏是重新安裝的日誌http://pastebin.com/pkxzZC9r – demas

怎麼是這樣的：編輯：使用StdRandom

import Data.Random hiding (shuffle) 
import Data.Random.Source.Std 
import Data.Random.Extras 

reversed = runRVar (shuffle "somestring") StdRandom 

test = do 
    x <- reversed 
    putStrLn x

來源

2012-10-29 12:19:08

我已經更新了我的問題：我無法導入Data.Random.Source.DevRandom – demas

好像'DevRandom'在Windows上不可用。不過，來自圖書館的不同隨機資源應該這樣做。 – kosmikus

我已更新爲使用StdRandom。這是否工作@demas？ –

轉換Data.RVar.RVar [字符]至[字符]

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