GHCJS可以重用由模板生成的代碼Haskell

此時GHCJS無法編譯postgresql-simple包（請參閱[1]）。我想用persistent包生成數據庫模型。我想知道是否可以使用GHC自己編譯模型，並重新使用由GHCJS源代碼中的模板Haskell生成的代碼？GHCJS可以重用由模板生成的代碼Haskell

我對我的問題已經有了解決方法，但問題仍然是相關的。我將把它打開幾天，如果沒有人會回答如何使用模板Haskell生成的代碼，我會關閉它。我在底部粘貼了結果代碼。

UPDATE：
thomie建議我-dth-dec-file標誌，它可以寫成模型文件語言編譯，例如{-# OPTIONS_GHC -dth-dec-file #-}。然後在運行stack build命令後，在.stack-work/dist/<arch>/<cabal-version>/build/src文件夾下有一個文件Model.th.hs。這個文件看起來像有效的Haskell，但是由於解析錯誤，GHC拒絕它（見底部的代碼）。但是，我發現了一種使用GHCJS編譯模型的方法。我在小集團文件添加條件，從依賴除去postgresql-simple：通過模板哈斯克爾產生

-- project.cabal 
library 
    -- ... 
    if impl(ghcjs) 
    build-depends:  persistent 
         , persistent-template 
    else 
    build-depends:  persistent 
         , persistent-postgresql 
         , persistent-template 
         , postgresql-simple

代碼（測試此代碼我複製項目源文件夾此文件，並添加在頂層模塊聲明）

-- src/Model.hs:(16,1)-(17,54): Splicing declarations 
instance Database.Persist.Class.PersistField.PersistField Manufacturer where 
    Database.Persist.Class.PersistField.toPersistValue 
    = \ ent_a9ov 
     -> (Database.Persist.Types.Base.PersistMap 
      GHC.Base.$ 
       (GHC.List.zip 
       (GHC.Base.map Data.Text.pack ["name"]) 
       ((GHC.Base.map Database.Persist.Class.PersistField.toPersistValue) 
        GHC.Base.$ 
        (Database.Persist.Class.PersistEntity.toPersistFields ent_a9ov)))) 
    Database.Persist.Class.PersistField.fromPersistValue 
    = ((\ x_a9ow 
      -> let columns_a9ox = Data.HashMap.Strict.fromList x_a9ow 
      in 
       (Database.Persist.Class.PersistEntity.fromPersistValues 
       GHC.Base.$ 
        ((GHC.Base.map 
         (\ name_a9oy 
         -> case 
           Data.HashMap.Base.lookup (Data.Text.pack name_a9oy) columns_a9ox 
          of { 
           GHC.Base.Just v_a9oz -> v_a9oz 
           GHC.Base.Nothing -> Database.Persist.Types.Base.PersistNull })) 
        GHC.Base.$ ["name"]))) 
     Control.Monad.<=< 
     Database.Persist.Class.PersistField.getPersistMap) 
instance Database.Persist.Sql.Class.PersistFieldSql Manufacturer where 
    Database.Persist.Sql.Class.sqlType _ 
    = Database.Persist.Types.Base.SqlString 
data Manufacturer 
    = Manufacturer {manufacturerName :: !Text} 
    deriving (Show, Read, Typeable) 
type ManufacturerId = 
    Database.Persist.Class.PersistEntity.Key Manufacturer 
instance Database.Persist.Class.PersistEntity.PersistEntity Manufacturer where 
    type Database.Persist.Class.PersistEntity.PersistEntityBackend Manufacturer = Database.Persist.Sql.Types.SqlBackend 
    data Database.Persist.Class.PersistEntity.Unique Manufacturer 
    = UniqueManufacturer Text 
    newtype Database.Persist.Class.PersistEntity.Key Manufacturer 
    = ManufacturerKey {unManufacturerKey :: Database.Persist.Class.PersistStore.BackendKey Database.Persist.Sql.Types.SqlBackend} 
    deriving (GHC.Show.Show, 
       GHC.Read.Read, 
       GHC.Classes.Eq, 
       GHC.Classes.Ord, 
       Web.PathPieces.PathPiece, 
       Web.HttpApiData.Internal.ToHttpApiData, 
       Web.HttpApiData.Internal.FromHttpApiData, 
       Database.Persist.Class.PersistField.PersistField, 
       Database.Persist.Sql.Class.PersistFieldSql, 
       Data.Aeson.Types.Class.ToJSON, 
       Data.Aeson.Types.Class.FromJSON) 
    data Database.Persist.Class.PersistEntity.EntityField Manufacturer typ 
    = typ ~ Database.Persist.Class.PersistEntity.Key Manufacturer => 
     ManufacturerId | 
     typ ~ Text => ManufacturerName 
    Database.Persist.Class.PersistEntity.keyToValues 
    = ((GHC.Types.: []) 
     GHC.Base.. 
     (Database.Persist.Class.PersistField.toPersistValue 
      GHC.Base.. unManufacturerKey)) 
    Database.Persist.Class.PersistEntity.keyFromValues 
    = ((GHC.Base.fmap ManufacturerKey) 
     GHC.Base.. 
     (Database.Persist.Class.PersistField.fromPersistValue 
      GHC.Base.. Database.Persist.TH.headNote)) 
    Database.Persist.Class.PersistEntity.entityDef _ 
    = Database.Persist.Types.Base.EntityDef 
     (Database.Persist.Types.Base.HaskellName 
      (Database.Persist.TH.packPTH "Manufacturer")) 
     (Database.Persist.Types.Base.DBName 
      (Database.Persist.TH.packPTH "manufacturer")) 
     (Database.Persist.Types.Base.FieldDef 
      (Database.Persist.Types.Base.HaskellName 
       (Database.Persist.TH.packPTH "Id")) 
      (Database.Persist.Types.Base.DBName 
       (Database.Persist.TH.packPTH "id")) 
      (Database.Persist.Types.Base.FTTypeCon 
       GHC.Base.Nothing (Database.Persist.TH.packPTH "ManufacturerId")) 
      Database.Persist.Types.Base.SqlInt64 
      [] 
      GHC.Types.True 
      (Database.Persist.Types.Base.ForeignRef 
       (Database.Persist.Types.Base.HaskellName 
       (Database.Persist.TH.packPTH "Manufacturer")) 
       (Database.Persist.Types.Base.FTTypeCon 
       (GHC.Base.Just (Database.Persist.TH.packPTH "Data.Int")) 
       (Database.Persist.TH.packPTH "Int64")))) 
     [Database.Persist.TH.packPTH "json"] 
     [Database.Persist.Types.Base.FieldDef 
      (Database.Persist.Types.Base.HaskellName 
       (Database.Persist.TH.packPTH "name")) 
      (Database.Persist.Types.Base.DBName 
       (Database.Persist.TH.packPTH "name")) 
      (Database.Persist.Types.Base.FTTypeCon 
       GHC.Base.Nothing (Database.Persist.TH.packPTH "Text")) 
      Database.Persist.Types.Base.SqlString 
      [] 
      GHC.Types.True 
      Database.Persist.Types.Base.NoReference] 
     [Database.Persist.Types.Base.UniqueDef 
      (Database.Persist.Types.Base.HaskellName 
       (Database.Persist.TH.packPTH "UniqueManufacturer")) 
      (Database.Persist.Types.Base.DBName 
       (Database.Persist.TH.packPTH "unique_manufacturer")) 
      [(Database.Persist.Types.Base.HaskellName 
       (Database.Persist.TH.packPTH "name"), 
      Database.Persist.Types.Base.DBName 
       (Database.Persist.TH.packPTH "name"))] 
      []] 
     [] 
     [Database.Persist.TH.packPTH "Show", 
     Database.Persist.TH.packPTH "Read", 
     Database.Persist.TH.packPTH "Typeable"] 
     (Data.Map.Base.fromList []) 
     GHC.Types.False 
    Database.Persist.Class.PersistEntity.toPersistFields 
    (Manufacturer x_a9oA) 
    = [Database.Persist.Class.PersistField.SomePersistField x_a9oA] 
    Database.Persist.Class.PersistEntity.fromPersistValues [x1_a9oC] 
    = Manufacturer 
     Data.Functor.<$> 
     ((Database.Persist.TH.mapLeft 
      (Database.Persist.TH.fieldError 
       (Database.Persist.TH.packPTH "name"))) 
     GHC.Base.. Database.Persist.Class.PersistField.fromPersistValue) 
      x1_a9oC 
    Database.Persist.Class.PersistEntity.fromPersistValues x_a9oB 
    = (Data.Either.Left 
     GHC.Base.$ 
     (GHC.Base.mappend 
      (Database.Persist.TH.packPTH 
       "Manufacturer: fromPersistValues failed on: ") 
      (Data.Text.pack GHC.Base.$ (GHC.Show.show x_a9oB)))) 
    Database.Persist.Class.PersistEntity.persistUniqueToFieldNames 
    (UniqueManufacturer {}) 
    = [(Database.Persist.Types.Base.HaskellName 
      (Database.Persist.TH.packPTH "name"), 
     Database.Persist.Types.Base.DBName 
      (Database.Persist.TH.packPTH "name"))] 
    Database.Persist.Class.PersistEntity.persistUniqueToValues 
    (UniqueManufacturer x_a9oD) 
    = [Database.Persist.Class.PersistField.toPersistValue x_a9oD] 
    Database.Persist.Class.PersistEntity.persistUniqueKeys 
    (Manufacturer _name_a9oE) 
    = [UniqueManufacturer _name_a9oE] 
    Database.Persist.Class.PersistEntity.persistFieldDef ManufacturerId 
    = Database.Persist.Types.Base.FieldDef 
     (Database.Persist.Types.Base.HaskellName 
      (Database.Persist.TH.packPTH "Id")) 
     (Database.Persist.Types.Base.DBName 
      (Database.Persist.TH.packPTH "id")) 
     (Database.Persist.Types.Base.FTTypeCon 
      GHC.Base.Nothing (Database.Persist.TH.packPTH "ManufacturerId")) 
     Database.Persist.Types.Base.SqlInt64 
     [] 
     GHC.Types.True 
     (Database.Persist.Types.Base.ForeignRef 
      (Database.Persist.Types.Base.HaskellName 
       (Database.Persist.TH.packPTH "Manufacturer")) 
      (Database.Persist.Types.Base.FTTypeCon 
       (GHC.Base.Just (Database.Persist.TH.packPTH "Data.Int")) 
       (Database.Persist.TH.packPTH "Int64"))) 
    Database.Persist.Class.PersistEntity.persistFieldDef 
    ManufacturerName 
    = Database.Persist.Types.Base.FieldDef 
     (Database.Persist.Types.Base.HaskellName 
      (Database.Persist.TH.packPTH "name")) 
     (Database.Persist.Types.Base.DBName 
      (Database.Persist.TH.packPTH "name")) 
     (Database.Persist.Types.Base.FTTypeCon 
      GHC.Base.Nothing (Database.Persist.TH.packPTH "Text")) 
     Database.Persist.Types.Base.SqlString 
     [] 
     GHC.Types.True 
     Database.Persist.Types.Base.NoReference 
    Database.Persist.Class.PersistEntity.persistIdField 
    = ManufacturerId 
    Database.Persist.Class.PersistEntity.fieldLens ManufacturerId 
    = Database.Persist.TH.lensPTH 
     Database.Persist.Class.PersistEntity.entityKey 
     (\ (Database.Persist.Class.PersistEntity.Entity _ value_a9oF) 
      key_a9oG 
      -> Database.Persist.Class.PersistEntity.Entity key_a9oG value_a9oF) 
    Database.Persist.Class.PersistEntity.fieldLens ManufacturerName 
    = Database.Persist.TH.lensPTH 
     (manufacturerName 
     GHC.Base.. Database.Persist.Class.PersistEntity.entityVal) 
     (\ (Database.Persist.Class.PersistEntity.Entity key_a9oH 
                 value_a9oI) 
      x_a9oJ 
      -> Database.Persist.Class.PersistEntity.Entity 
       key_a9oH (value_a9oI {manufacturerName = x_a9oJ})) 
instance Database.Persist.Class.PersistStore.ToBackendKey Database.Persist.Sql.Types.SqlBackend Manufacturer where 
    Database.Persist.Class.PersistStore.toBackendKey 
    = unManufacturerKey 
    Database.Persist.Class.PersistStore.fromBackendKey 
    = ManufacturerKey 
instance Data.Aeson.Types.Class.ToJSON Manufacturer where 
    Data.Aeson.Types.Class.toJSON (Manufacturer name_a9oL) 
    = Data.Aeson.Types.Internal.object 
     [((Data.Text.pack "name") Data.Aeson.Types.Instances..= name_a9oL)] 
instance Data.Aeson.Types.Class.FromJSON Manufacturer where 
    Data.Aeson.Types.Class.parseJSON 
    (Data.Aeson.Types.Internal.Object obj_a9oK) 
    = ((GHC.Base.pure Manufacturer) 
     GHC.Base.<*> 
     (obj_a9oK Data.Aeson.Types.Instances..: (Data.Text.pack "name"))) 
    Data.Aeson.Types.Class.parseJSON _ = GHC.Base.mzero 
instance Data.Aeson.Types.Class.ToJSON (Database.Persist.Class.PersistEntity.Entity Manufacturer) where 
    Data.Aeson.Types.Class.toJSON 
    = Database.Persist.Class.PersistEntity.entityIdToJSON 
instance Data.Aeson.Types.Class.FromJSON (Database.Persist.Class.PersistEntity.Entity Manufacturer) where 
    Data.Aeson.Types.Class.parseJSON 
    = Database.Persist.Class.PersistEntity.entityIdFromJSON 
migrateAll :: Database.Persist.Sql.Types.Migration 
migrateAll 
    = do { let defs_a9oM 
       = [Database.Persist.Types.Base.EntityDef 
        (Database.Persist.Types.Base.HaskellName 
         (Database.Persist.TH.packPTH "Manufacturer")) 
        (Database.Persist.Types.Base.DBName 
         (Database.Persist.TH.packPTH "manufacturer")) 
        (Database.Persist.Types.Base.FieldDef 
         (Database.Persist.Types.Base.HaskellName 
          (Database.Persist.TH.packPTH "Id")) 
         (Database.Persist.Types.Base.DBName 
          (Database.Persist.TH.packPTH "id")) 
         (Database.Persist.Types.Base.FTTypeCon 
          GHC.Base.Nothing (Database.Persist.TH.packPTH "ManufacturerId")) 
         Database.Persist.Types.Base.SqlInt64 
         [] 
         GHC.Types.True 
         (Database.Persist.Types.Base.ForeignRef 
          (Database.Persist.Types.Base.HaskellName 
          (Database.Persist.TH.packPTH "Manufacturer")) 
          (Database.Persist.Types.Base.FTTypeCon 
          (GHC.Base.Just (Database.Persist.TH.packPTH "Data.Int")) 
          (Database.Persist.TH.packPTH "Int64")))) 
        [Database.Persist.TH.packPTH "json"] 
        [Database.Persist.Types.Base.FieldDef 
         (Database.Persist.Types.Base.HaskellName 
          (Database.Persist.TH.packPTH "name")) 
         (Database.Persist.Types.Base.DBName 
          (Database.Persist.TH.packPTH "name")) 
         (Database.Persist.Types.Base.FTTypeCon 
          GHC.Base.Nothing (Database.Persist.TH.packPTH "Text")) 
         Database.Persist.Types.Base.SqlString 
         [] 
         GHC.Types.True 
         Database.Persist.Types.Base.NoReference] 
        [Database.Persist.Types.Base.UniqueDef 
         (Database.Persist.Types.Base.HaskellName 
          (Database.Persist.TH.packPTH "UniqueManufacturer")) 
         (Database.Persist.Types.Base.DBName 
          (Database.Persist.TH.packPTH "unique_manufacturer")) 
         [(Database.Persist.Types.Base.HaskellName 
          (Database.Persist.TH.packPTH "name"), 
         Database.Persist.Types.Base.DBName 
          (Database.Persist.TH.packPTH "name"))] 
         []] 
        [] 
        [Database.Persist.TH.packPTH "Show", 
        Database.Persist.TH.packPTH "Read", 
        Database.Persist.TH.packPTH "Typeable"] 
        (Data.Map.Base.fromList []) 
        GHC.Types.False]; 
     Database.Persist.Sql.Migration.migrate 
      defs_a9oM 
      (Database.Persist.Types.Base.EntityDef 
       (Database.Persist.Types.Base.HaskellName 
       (Database.Persist.TH.packPTH "Manufacturer")) 
       (Database.Persist.Types.Base.DBName 
       (Database.Persist.TH.packPTH "manufacturer")) 
       (Database.Persist.Types.Base.FieldDef 
       (Database.Persist.Types.Base.HaskellName 
        (Database.Persist.TH.packPTH "Id")) 
       (Database.Persist.Types.Base.DBName 
        (Database.Persist.TH.packPTH "id")) 
       (Database.Persist.Types.Base.FTTypeCon 
        GHC.Base.Nothing (Database.Persist.TH.packPTH "ManufacturerId")) 
       Database.Persist.Types.Base.SqlInt64 
       [] 
       GHC.Types.True 
       (Database.Persist.Types.Base.ForeignRef 
        (Database.Persist.Types.Base.HaskellName 
         (Database.Persist.TH.packPTH "Manufacturer")) 
        (Database.Persist.Types.Base.FTTypeCon 
         (GHC.Base.Just (Database.Persist.TH.packPTH "Data.Int")) 
         (Database.Persist.TH.packPTH "Int64")))) 
       [Database.Persist.TH.packPTH "json"] 
       [Database.Persist.Types.Base.FieldDef 
       (Database.Persist.Types.Base.HaskellName 
        (Database.Persist.TH.packPTH "name")) 
       (Database.Persist.Types.Base.DBName 
        (Database.Persist.TH.packPTH "name")) 
       (Database.Persist.Types.Base.FTTypeCon 
        GHC.Base.Nothing (Database.Persist.TH.packPTH "Text")) 
       Database.Persist.Types.Base.SqlString 
       [] 
       GHC.Types.True 
       Database.Persist.Types.Base.NoReference] 
       [Database.Persist.Types.Base.UniqueDef 
       (Database.Persist.Types.Base.HaskellName 
        (Database.Persist.TH.packPTH "UniqueManufacturer")) 
       (Database.Persist.Types.Base.DBName 
        (Database.Persist.TH.packPTH "unique_manufacturer")) 
       [(Database.Persist.Types.Base.HaskellName 
        (Database.Persist.TH.packPTH "name"), 
        Database.Persist.Types.Base.DBName 
        (Database.Persist.TH.packPTH "name"))] 
       []] 
       [] 
       [Database.Persist.TH.packPTH "Show", 
       Database.Persist.TH.packPTH "Read", 
       Database.Persist.TH.packPTH "Typeable"] 
       (Data.Map.Base.fromList []) 
       GHC.Types.False) }

錯誤消息報告解析錯誤的->上線開始GHC.Base.Nothing ->

(\ name_a9oy 
    -> case 
      Data.HashMap.Base.lookup (Data.Text.pack name_a9oy) columns_a9ox 
     of { 
      GHC.Base.Just v_a9oz -> v_a9oz 
      GHC.Base.Nothing -> Database.Persist.Types.Base.PersistNull }))

來源

2016-06-11 Geradlus_RU

編輯：您不能直接我將重用在ghc構建中生成的代碼，但您可以在ghcjs代碼中簡單地使用包含Persistent數據庫模型的模塊。這將生成和構建GHCJS的數據庫內容，然後可用於GHCJS代碼。

來源

2016-06-12 07:43:57

Hi @Martin Vik！你的意思是建立模塊與整個庫分開嗎？ –

是的，如果我避免了客戶端代碼的'postgresql-simple'依賴性，你的方法就可以工作。 –

GHCJS可以重用由模板生成的代碼Haskell

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