src/Rel8/Type/Num.hs · rel8

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1{-# language DataKinds #-}

2{-# language FlexibleContexts #-}

3{-# language FlexibleInstances #-}

4{-# language MultiParamTypeClasses #-}

5{-# language StandaloneKindSignatures #-}

6{-# language TypeFamilies #-}

7{-# language UndecidableInstances #-}

9module Rel8.Type.Num

10 ( DBNum, DBIntegral, DBFractional

11 )

12where

14-- base

15import Data.Int ( Int16, Int32, Int64 )

16import Data.Kind ( Constraint, Type )

17import Prelude

19-- rel8

20import Rel8.Type ( DBType )

22-- scientific

23import Data.Scientific ( Scientific )

26-- | The class of database types that support the @+@, @*@, @-@ operators, and

27-- the @abs@, @negate@, @sign@ functions.

28type DBNum :: Type -> Constraint

29class DBType a => DBNum a

30instance DBNum Int16

31instance DBNum Int32

32instance DBNum Int64

33instance DBNum Float

34instance DBNum Double

35instance DBNum Scientific

38-- | The class of database types that can be coerced to from integral

39-- expressions. This is a Rel8 concept, and allows us to provide

40-- 'fromIntegral'.

41type DBIntegral :: Type -> Constraint

42class DBNum a => DBIntegral a

43instance DBIntegral Int16

44instance DBIntegral Int32

45instance DBIntegral Int64

48-- | The class of database types that support the @/@ operator.

49class DBNum a => DBFractional a

50instance DBFractional Float

51instance DBFractional Double

52instance DBFractional Scientific