Question

我正在使用ghc 7.10.3在沙盒中工作，我有这个简单的代码：

main :: IO ()
main = do
  args <- getArgs
  case args of
    [ newOauthConsumerKey, newOauthConsumerSecret ] -> do
      let appOauth = newOAuth { oauthServerName       = "api.twitter.com"
                              , oauthConsumerKey    = newOauthConsumerKey
                              , oauthConsumerSecret = newOauthConsumerSecret
                              }
  ...

当我在我的cabal文件中使用这些依赖项编译它时：

base
, authenticate-oauth
, http-conduit
, aeson
, text

我继续得到（在清理和重建沙箱之后）以下错误：

src/Test/Main.hs:60:55:
    Couldn't match type ‘[Char]’
                   with ‘bytestring-0.10.6.0:Data.ByteString.Internal.ByteString’
    Expected type: bytestring-0.10.6.0:Data.ByteString.Internal.ByteString
      Actual type: String
    In the ‘oauthConsumerKey’ field of a record
    In the expression:
      newOAuth
        {oauthServerName = "api.twitter.com",
         oauthConsumerKey = newOauthConsumerKey,
         oauthConsumerSecret = newOauthConsumerSecret}

src/Test/Main.hs:61:55:
    Couldn't match type ‘[Char]’
                   with ‘bytestring-0.10.6.0:Data.ByteString.Internal.ByteString’
    Expected type: bytestring-0.10.6.0:Data.ByteString.Internal.ByteString
      Actual type: String
    In the ‘oauthConsumerSecret’ field of a record
    In the expression:
      newOAuth
        {oauthServerName = "api.twitter.com",
         oauthConsumerKey = newOauthConsumerKey,
         oauthConsumerSecret = newOauthConsumerSecret}

我已经使用Google搜索并检查了不同类似的答案，但我无法使其正常工作。有什么想法吗？

解决方案

问题原因在于代码中import Data.Text的导入包含pack，与pack所需的Data.ByteString.Char8不同。一旦我加入它，它就有用了。

Answer 1

字段oauthConsumerKey和oauthConsumerSecret应该包含ByteString s而不是String s，这是getArgs返回的内容。您需要使用pack转换newOauthConsumer*值。

Haskell：当我使用getArgs时ByteString问题

1 个答案: