2c0e6a5 · typeable/postgresql-simple

git.iko.soy/typeable/postgresql-simple

Add To/FromField instances for Const

commit2c0e6a5c656299af5d1457c7bbd74c5a50e23f21 authorCary Robbins <carymrobbins@gmail.com> dateFri 7 Aug 2020, 08:27 (6 years ago) parent265a519

3 files changed+24−2

compare with master

unifiedsplit

CHANGES.md+4−1 src/Database/PostgreSQL/Simple/FromField.hs+9−1 src/Database/PostgreSQL/Simple/ToField.hs+11

CHANGES.md+4−1

@@ -2,10 +2,13 @@

33 * Add `fromFieldJSONByteString`

44 Thanks to tomjaguarpaw for the implementation

5− https://github.com/lpsmith/postgresql-simple/pull/222

5+ https://github.com/haskellari/postgresql-simple/pull/47

66 * Add `attoFieldParser`

77 Thanks to Victor Nawothnig for the implementation

88 https://github.com/haskellari/postgresql-simple/pull/45

9+ * Add `Identity` and `Const` instance

10+ Thanks to Cary Robbins for the implementation

11+ https://github.com/haskellari/postgresql-simple/pull/46

912

1013### Version 0.6.2 (2019-04-26)

1114

src/Database/PostgreSQL/Simple/FromField.hs+9−1

@@ -2,6 +2,7 @@

22{-# LANGUAGE FlexibleInstances, TypeSynonymInstances #-}

33{-# LANGUAGE PatternGuards, ScopedTypeVariables #-}

44{-# LANGUAGE RecordWildCards #-}

5+{-# LANGUAGE PolyKinds #-}

67{- |

78Module: Database.PostgreSQL.Simple.FromField

@@ -115,7 +116,7 @@ module Database.PostgreSQL.Simple.FromField

115116

116117#include "MachDeps.h"

117118

118−import Control.Applicative ( (<|>), (<$>), pure, (*>), (<*) )

119+import Control.Applicative ( Const(Const), (<|>), (<$>), pure, (*>), (<*) )

119120import Control.Concurrent.MVar (MVar, newMVar)

120121import Control.Exception (Exception)

121122import qualified Data.Aeson as JSON

@@ -124,6 +125,7 @@ import qualified Data.Aeson.Parser as JSON (value')

124125import Data.Attoparsec.ByteString.Char8 hiding (Result)

125126import Data.ByteString (ByteString)

126127import qualified Data.ByteString.Char8 as B

128+import Data.Functor.Identity (Identity(Identity))

127129import Data.Int (Int16, Int32, Int64)

128130import Data.IORef (IORef, newIORef)

129131import Data.Ratio (Ratio)

@@ -269,6 +271,12 @@ instance FromField () where

269271 | typeOid f /= TI.voidOid = returnError Incompatible f ""

270272 | otherwise = pure ()

271273

274+instance (FromField a) => FromField (Const a b) where

275+ fromField f bs = Const <$> fromField f bs

276+

277+instance (FromField a) => FromField (Identity a) where

278+ fromField f bs = Identity <$> fromField f bs

279+

272280-- | For dealing with null values. Compatible with any postgresql type

273281-- compatible with type @a@. Note that the type is not checked if

274282-- the value is null, although it is inadvisable to rely on this

src/Database/PostgreSQL/Simple/ToField.hs+11

@@ -1,5 +1,6 @@

11{-# LANGUAGE CPP, DeriveDataTypeable, DeriveFunctor #-}

22{-# LANGUAGE FlexibleInstances, TypeSynonymInstances #-}

3+{-# LANGUAGE PolyKinds #-}

45------------------------------------------------------------------------------

56-- |

@@ -22,6 +23,7 @@ module Database.PostgreSQL.Simple.ToField

2223 , inQuotes

2324 ) where

2425

26+import Control.Applicative (Const(Const))

2527import qualified Data.Aeson as JSON

2628import Data.ByteString (ByteString)

2729import Data.ByteString.Builder

@@ -30,6 +32,7 @@ import Data.ByteString.Builder

3032 , wordDec, word8Dec, word16Dec, word32Dec, word64Dec

3133 , floatDec, doubleDec

3234 )

35+import Data.Functor.Identity (Identity(Identity))

3336import Data.Int (Int8, Int16, Int32, Int64)

3437import Data.List (intersperse)

3538import Data.Monoid (mappend)

@@ -100,6 +103,14 @@ instance ToField Action where

100103 toField a = a

101104 {-# INLINE toField #-}

102105

106+instance (ToField a) => ToField (Const a b) where

107+ toField (Const a) = toField a

108+ {-# INLINE toField #-}

109+

110+instance (ToField a) => ToField (Identity a) where

111+ toField (Identity a) = toField a

112+ {-# INLINE toField #-}

113+

103114instance (ToField a) => ToField (Maybe a) where

104115 toField Nothing = renderNull

105116 toField (Just a) = toField a