Haskell 从数据库检索消化函子的选项列表（快照/抢劫）

我有一个地址表，可以处理添加和编辑（如果添加，则无需任何内容，如果编辑，则只需地址）。到目前为止，我已经把州和国家的选择硬编码为几个项目

addressForm :: Monad m => Maybe Address -> [Address] -> Form Text m Address
addressForm a addrs = 
    Address
        <$> "id" .: choiceWith (addrToChoice addrs) (fmap id a)
        <*> "name" .: string (fmap name a)
        <*> "street" .: string (fmap street a)
        <*> "city" .: string (fmap city a)
        <*> "state" .: choiceWith stateChoices (fmap state a)
        <*> "country" .: choiceWith countryChoicesRequired (fmap country a)
        <*> "zipcode" .: string (fmap zipcode a)


stateChoices :: [(Text, (Maybe String, Text))] -- (htmlValue, (realValue, labelValue))
stateChoices = [("ON", (Just "ON", "Ontario")), ("NE", (Just "NE", "Nebraska"))]

countryChoicesRequired :: [(Text, (String, Text))]
countryChoicesRequired = [("CA", ("CA", "Canada")), ("US", ("US", "United States of America"))]

addressForm:：Monad m=>可能的地址->[Address]->Form Text m地址
地址格式a地址=
地址
“id”。：choiceWith（地址选择地址）（fmap id a）
“名称”。：字符串（fmap名称a）
“street.”：字符串（fmap street a）
“城市”。：字符串（fmap城市a）
“状态”。：选择状态选项（fmap状态a）
“国家”。：选择需要国家选项（fmap国家a）
“zipcode”：字符串（fmap zipcode a）
状态选项：：[（文本，（可能是字符串，文本））]-（htmlValue，（realValue，labelValue））
州选项=[（“ON”，“ON”，“安大略省”），（“NE”，“NE”，“内布拉斯加州”）]
countryChoicesRequired:：[（文本，（字符串，文本））]
countryChoicesRequired=[（（“CA”，“加拿大”），（“美国”，“美国”）]

现在我想从数据库中检索州和国家的列表。我可以像处理地址列表一样将州/国家列表传递给表单，但此表单也是3或4个其他表单（新广告商表单、新客户表单等）的子表单，我不需要表单之外的州/国家列表，就像处理地址列表一样

这是我刚刚添加的获取国家信息的新表单：

addressForm' :: (HasPostgres p, Monad m) => Maybe Address -> [Address] -> p (Form Text m Address)
addressForm' a addrs = do
    countries <- countryChoices'
    return $ Address
        <$> "id" .: choiceWith (addrToChoice addrs) (fmap id a)
        <*> "name" .: string (fmap name a)
        <*> "street" .: string (fmap street a)
        <*> "city" .: string (fmap city a)
        <*> "state" .: choiceWith stateChoices (fmap state a)
        <*> "country" .: choiceWith countries (fmap country a)
        <*> "zipcode" .: string (fmap zipcode a)

data Region = Region
    { code :: String
    , fullName :: String
    }

countryChoices' :: HasPostgres m => m [(Text, (String, Text))]
countryChoices' = do
    countries <- getCountries
    return $ abbrToChoice countries

abbrToChoice :: [Region] -> [(Text, (String, Text))]
abbrToChoice regions =
    map (\ a -> ((pack $ code a), (code a, (pack $ fullName a)))) regions

addressForm'：：（HasPostgres p，Monad m）=>可能地址->[Address]->p（Form Text m Address）
addressForm'a addrs=do
国家m[（文本，（字符串，文本））]
countryChoices'=do
国家[（文本，（字符串，文本））]
阿巴托选择区=
映射（\a->（（pack$code a），（code a，（pack$fullName a）））区域

下面是调用它的处理程序：

editAddressH :: ([(T.Text, Splice AppHandler)] -> AppHandler ()) -> Addr.Address -> Maybe Int64 -> AppHandler ()
editAddressH renderer a userId = do
    addresses <- Addr.list userId
    (view, result) <- runForm "form" $ Addr.addressForm' (Just a) addresses -- line 233
    case result of
        Just x -> do
            r <- Addr.edit x -- line 236
            case r of
                _ -> renderer [("success", showContents), ("dfForm", hideContents)]
        Nothing -> renderer $ ("success", hideContents) : ("addressList", addressScriptSplice addresses) : phoneSplices ++ digestiveSplices view

editAddressH:：（[（T.Text，拼接AppHandler）]->AppHandler（））->Addr.Address->Maybe Int64->AppHandler（）
editAddressH呈现程序a userId=do
地址渲染器
$（“成功”，隐藏内容）
：（“地址列表”，地址脚本拼接地址）
：phoneSplices++digestiveSplices视图}
src/Site.hs:236:40:
无法匹配预期的类型“地址”
实际类型为'suscellate-funcors-0.5.0.1:Text.suscellate.Form.Internal.FormTree
m0文本m0地址'
应为类型：地址地址
实际类型：表单文本m0地址
在'Addr.edit'的第一个参数中，即'x'
在“do”表达式的stmt中：r看起来需要该函数。它可能看起来像这样：

addressForm :: Monad m => Maybe Address -> [Address] -> Form Text m Address
addressForm a addrs = monadic $ do
    stateChoices <- getStatesFromDB
    countryChoices <- getCountriesFromDB
    return $
      Address
          <$> "id" .: choiceWith (addrToChoice addrs) (fmap id a)
          <*> "name" .: string (fmap name a)
          <*> "street" .: string (fmap street a)
          <*> "city" .: string (fmap city a)
          <*> "state" .: choiceWith stateChoices (fmap state a)
          <*> "country" .: choiceWith countryChoices (fmap country a)
          <*> "zipcode" .: string (fmap zipcode a)

addressForm:：Monad m=>可能的地址->[Address]->Form Text m地址
地址形式a地址=一元$do
州选择
addressForm :: Monad m => Maybe Address -> [Address] -> Form Text m Address
addressForm a addrs = monadic $ do
    stateChoices <- getStatesFromDB
    countryChoices <- getCountriesFromDB
    return $
      Address
          <$> "id" .: choiceWith (addrToChoice addrs) (fmap id a)
          <*> "name" .: string (fmap name a)
          <*> "street" .: string (fmap street a)
          <*> "city" .: string (fmap city a)
          <*> "state" .: choiceWith stateChoices (fmap state a)
          <*> "country" .: choiceWith countryChoices (fmap country a)
          <*> "zipcode" .: string (fmap zipcode a)