src/Rel8/Schema/Field.hs · rel8

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1{-# language DataKinds #-}

2{-# language StandaloneKindSignatures #-}

3{-# language TypeFamilies #-}

4{-# language UndecidableInstances #-}

6module Rel8.Schema.Field

7 ( Field

8 )

9where

11-- base

12import Data.Kind ( Type )

13import Prelude

15-- rel8

16import Rel8.Aggregate ( Aggregate )

17import Rel8.Expr ( Expr )

18import Rel8.Kind.Labels ( Labels )

19import Rel8.Kind.Necessity ( Necessity( Required, Optional ) )

20import Rel8.Schema.Context

21 ( Aggregation, DB, Insertion, Result

22 , IsSpecialContext

23 )

24import Rel8.Schema.Spec ( Context, Spec( Spec ) )

25import Rel8.Schema.Structure ( Structure, Shape( Column ), Shape1 )

28type IField :: Bool -> Context -> Labels -> Necessity -> Type -> Type -> Type

29type family IField isSpecialContext labels context necessity db a where

30 IField 'False context labels necessity db a = context ('Spec labels necessity db a)

31 IField 'True Result _labels _necessity _db a = a

32 IField 'True DB _labels _necessity _db a = Expr a

33 IField 'True Insertion _labels 'Required _db a = Expr a

34 IField 'True Insertion _labels 'Optional _db a = Maybe (Expr a)

35 IField 'True Aggregation _labels _necessity _db a = Aggregate (Expr a)

36 IField 'True Structure labels necessity db a = Shape1 'Column ('Spec labels necessity db a)

39type Field :: Context -> Labels -> Necessity -> Type -> Type -> Type

40type Field context labels necessity db a =

41 IField (IsSpecialContext context) context labels necessity db a