src/Rel8/Type/String.hs · rel8

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rel8/src/Rel8/Type/String.hs

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1{-# language FlexibleContexts #-}

2{-# language FlexibleInstances #-}

3{-# language MultiParamTypeClasses #-}

4{-# language StandaloneKindSignatures #-}

5{-# language UndecidableInstances #-}

7module Rel8.Type.String

8 ( DBString

9 )

10where

12-- base

13import Data.Kind ( Constraint, Type )

14import Prelude ()

16-- bytestring

17import Data.ByteString ( ByteString )

18import qualified Data.ByteString.Lazy as Lazy ( ByteString )

20-- case-insensitive

21import Data.CaseInsensitive ( CI )

23-- rel8

24import Rel8.Schema.Nullability ( HasNullability, Unnullify, Sql )

25import Rel8.Type ( DBType )

27-- text

28import Data.Text ( Text )

29import qualified Data.Text.Lazy as Lazy ( Text )

32-- | The class of data types that support the @string_agg()@ aggregation

33-- function.

34type DBString :: Type -> Constraint

35class DBType a => DBString a

36instance DBString Text

37instance DBString Lazy.Text

38instance DBString (CI Text)

39instance DBString (CI Lazy.Text)

40instance DBString ByteString

41instance DBString Lazy.ByteString

44instance {-# INCOHERENT #-} (HasNullability a, DBString (Unnullify a)) =>

45 Sql DBString a