無法與yesod博客示例中的預期類型相匹配

我試圖讓博客示例運行，但在某些處理函數中存在類型問題，我不知道如何解決該問題。無法與yesod博客示例中的預期類型相匹配

我試圖運行在此發佈的例子： Yesod blog example 我改變一點點，我添加類型defaultLayout功能，並使其耶索德的實例來擺脫雙重定義。

defLayout :: GWidget a Blog() -> GHandler a Blog RepHtml 
defLayout inside = do 
    mmsg <- getMessage 
    pc <- widgetToPageContent $ do 
     toWidget [lucius| 
body { 
width: 760px; 
margin: 1em auto; 
font-family: sans-serif; 
} 
textarea { 
width: 400px; 
height: 200px; 
} 
#message { 
color: #900; 
} 
|] 
     inside 
    hamletToRepHtml [hamlet| 
$doctype 5 
<html> 
    <head> 
     <title>#{pageTitle pc} 
     ^{pageHead pc} 
    <body> 
     $maybe msg <- mmsg 
      <div #message>#{msg} 
     ^{pageBody pc} 
|] 

instance Yesod Blog where 
    approot = ApprootStatic "http://localhost:3000" 
    defaultLayout = defLayout

這些是給我的問題的功能：

getBlogR :: Handler RepHtml 
getBlogR = do 
    muser <- maybeAuth 
    entries <- runDB $ selectList [] [Desc EntryPosted] 
    ((_, entryWidget), enctype) <- generateFormPost entryForm 
    defaultLayout $ do 
      setTitleI MsgBlogArchiveTitle 
      [whamlet| 
$if null entries 
    <p>_{MsgNoEntries} 
$else 
    <ul> 
     $forall Entity entryId entry <- entries 
      <li> 
       <a [email protected]{EntryR entryId}>#{entryTitle entry} 
$maybe Entity _ user <- muser 
    $if isAdmin user 
     <form method=post enctype=#{enctype}> 
       ^{entryWidget} 
       <div> 
        <input type=submit value=_{MsgNewEntry}> 
$nothing 
    <p> 
     <a [email protected]{AuthR LoginR}>_{MsgLoginToPost} 
|] 

getEntryR :: EntryId -> Handler RepHtml 
getEntryR entryId = do 
    (entry, comments) <- runDB $ do 
      entry <- get404 entryId 
      comments <- selectList [] [Asc CommentPosted] 
      return (entry, map entityVal comments) 
    muser <- maybeAuth 
    ((_, commentWidget), enctype) <- generateFormPost (commentForm entryId) 
    defaultLayout $ do 
    setTitleI $ MsgEntryTitle $ entryTitle entry 
    [whamlet| 
<h1>#{entryTitle entry} 
<article>#{entryContent entry} 
    <section .comments> 
     <h1>_{MsgCommentsHeading} 
     $if null comments 
      <p>_{MsgNoComments} 
     $else 
      $forall Comment _entry posted _user name text <- comments 
       <div .comment> 
         <span .by>#{name} 
         <span .at>#{show posted} 
         <div .content>#{text} 
     <section> 
      <h1>_{MsgAddCommentHeading} 
      $maybe _ <- muser 
       <form method=post enctype=#{enctype}> 
        ^{commentWidget} 
        <div> 
         <input type=submit value=_{MsgAddCommentButton}> 
      $nothing 
       <p> 
        <a [email protected]{AuthR LoginR}>_{MsgLoginToComment} 
|]

這裏的輸出我得到的，當我嘗試運行它：

blog.hs:147:4: 
    Couldn't match expected type `GWidget Blog Blog()' 
       with actual type `(t0, t1)' 
    In the pattern: (_, entryWidget) 
    In the pattern: ((_, entryWidget), enctype) 
    In a stmt of a 'do' block: 
     ((_, entryWidget), enctype) <- generateFormPost entryForm 

blog.hs:202:4: 
    Couldn't match expected type `GWidget Blog Blog()' 
       with actual type `(t0, t1)' 
    In the pattern: (_, commentWidget) 
    In the pattern: ((_, commentWidget), enctype) 
    In a stmt of a 'do' block: 
     ((_, commentWidget), enctype) <- generateFormPost 
             (commentForm entryId)

來源

2012-08-07 Altair

類型的generateFormPost已經改變博客文章，它曾經是

generateFormPost :: RenderMessage master FormMessage => 
        (Html -> MForm sub master (FormResult a, xml)) -> 
        GHandler sub master ((FormResult a, xml), Enctype)

在yesod-form-0.4.*但now它

generateFormPost :: RenderMessage master FormMessage => 
        (Markup -> MForm sub master (FormResult a, xml)) -> 
        GHandler sub master (xml, Enctype)

應[我認爲，從來沒有使用過耶索德該類型的錯誤消失，如果你使用yesod-form < 1，或者如果你有

(entryWidget, enctype) <- generateFormPost entryForm

更換

((_, entryWidget), enctype) <- generateFormPost entryForm

反映generateFormPost類型的變化。

來源

2012-08-07 13:14:39

謝謝你，那是做的。沒有意識到類型已經改變。 – Altair 2012-08-07 13:24:41

無法與yesod博客示例中的預期類型相匹配

回答

相關問題