Yesod，Persistent和MySQL没有实例错误

我不确定在这篇文章中包含什么内容，因为我真的不理解错误消息，所以我只包含了错误，Model.hs文件和模型。我正在使用Yesod MySQL脚手架网站。我正在使用的操作系统是Ubuntu。如果您需要查看其他任何代码，例如数据定义，则只需询问即可。

错误信息：

[ 6 of 20] Compiling Model            ( src/Model.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.2.0/build/Model.o )

/home/james/ConVoke/convoke-website/src/Model.hs:24:7: error:
    • No instance for (persistent-2.7.0:Database.Persist.Sql.Class.PersistFieldSql
                         Language)
        arising from a use of ‘persistent-2.7.0:Database.Persist.Sql.Class.sqlType’
    • In the fourth argument of ‘FieldDef’, namely
        ‘persistent-2.7.0:Database.Persist.Sql.Class.sqlType
           (Data.Proxy.Proxy :: Data.Proxy.Proxy Language)’
      In the expression:
        FieldDef
          (HaskellName (packPTH "language"))
          (DBName (packPTH "language"))
          (FTTypeCon Nothing (packPTH "Language"))
          (persistent-2.7.0:Database.Persist.Sql.Class.sqlType
             (Data.Proxy.Proxy :: Data.Proxy.Proxy Language))
          []
          True
          NoReference
      In the ‘entityFields’ field of a record

--  While building package website-0.0.0 using:
      /home/james/.stack/setup-exe-cache/x86_64-linux/Cabal-simple_mPHDZzAJ_1.24.2.0_ghc-8.0.2 --builddir=.stack-work/dist/x86_64-linux/Cabal-1.24.2.0 build lib:website --ghc-options " -ddump-hi -ddump-to-file"

型号：

{-# LANGUAGE EmptyDataDecls             #-}
{-# LANGUAGE FlexibleInstances          #-}
{-# LANGUAGE GADTs                      #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses      #-}
{-# LANGUAGE NoImplicitPrelude          #-}
{-# LANGUAGE OverloadedStrings          #-}
{-# LANGUAGE TemplateHaskell            #-}
{-# LANGUAGE TypeFamilies               #-}
module Model where

import ClassyPrelude.Yesod
import Database.Persist.Quasi

import Import.Game
import Import.Language
import Import.Profile

-- You can define all of your database entities in the entities file.
-- You can find more information on persistent and how to declare entities
-- at:
-- http://www.yesodweb.com/book/persistent/
share [mkPersist sqlSettings, mkMigrate "migrateAll"]
    $(persistFileWith lowerCaseSettings "config/models")

楷模：

Player
     name Text
     username Text
     dob Day
     language Language
     tournaments [TournamentResult]
     deriving (Show)

 PlatformAccount
     player PlayerId
     platform Platform
     account Text
     deriving (Show)

 SocialAccount
     player PlayerId
     site SocialSite
     account Text
     deriving (Show)

 PastTeam
     player PlayerId
     team TeamId
     yearJoined Int
     yearLeft Int
     deriving (Show)

 TournamentResult
     player PlayerId
     team TeamId
     name Text
     placing Text
     year Int
     deriving (Show)

 Roster
     name Text
     game Game
     team TeamId
     players [PlayerId]
     creationDay Day
     deriving (Show)

 PlayerRole
     roster RosterId
     player PlayerId
     role Role
     deriving (Show)

 CompetitiveGame
     game Game
     platform Platform
     role Role
     availability Availability
     playingSince Int
     deriving (Show)

 Team
     name Text
     creationDay Day
     deriving (Show)

提前致谢 ：）

编辑：根据要求定义Language数据类型的Language.hs文件：

module Import.Language where

allLanguages :: [Language]
allLanguages = [Afrikanns ..]

data Language = Afrikanns |
                Albanian |
                Arabic |
                Armenian |
                Basque |
                Bengali |
                Bulgarian |
                Catalan |
                Cambodian |
                Chinese_Mandarin |
                Croation |
                Czech |
                Danish |
                Dutch |
                English |
                Estonian |
                Fiji |
                Finnish |
                French |
                Georgian |
                German |
                Greek |
                Gujarati |
                Hebrew |
                Hindi |
                Hungarian |
                Icelandic |
                Indonesian |
                Irish |
                Italian |
                Japanese |
                Javanese |
                Korean |
                Latin |
                Latvian |
                Lithuanian |
                Macedonian |
                Malay |
                Malayalam |
                Maltese |
                Maori |
                Marathi |
                Mongolian |
                Nepali |
                Norwegian |
                Persian |
                Polish |
                Portuguese |
                Punjabi |
                Quechua |
                Romanian |
                Russian |
                Samoan |
                Serbian |
                Slovak |
                Slovenian |
                Spanish |
                Swahili |
                Swedish  |
                Tamil |
                Tatar |
                Telugu |
                Thai |
                Tibetan |
                Tonga |
                Turkish |
                Ukranian |
                Urdu |
                Uzbek |
                Vietnamese |
                Welsh |
                Xhosa
                deriving (Enum, Show, Eq)