src/Rel8/Table/NonEmpty.hs · rel8

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rel8/src/Rel8/Table/NonEmpty.hs

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1{-# language FlexibleInstances #-}

2{-# language MultiParamTypeClasses #-}

3{-# language StandaloneKindSignatures #-}

4{-# language TypeFamilies #-}

5{-# language UndecidableInstances #-}

7module Rel8.Table.NonEmpty

8 ( NonEmptyTable(..)

9 , HNonEmptyTable

10 )

11where

13-- base

14import Data.Kind ( Type )

15import Prelude

17-- rel8

18import Rel8.Expr.Array ( sappend1 )

19import Rel8.Schema.Context ( DB( DB ) )

20import Rel8.Schema.HTable.Context ( H )

21import Rel8.Schema.HTable.NonEmpty ( HNonEmptyTable )

22import Rel8.Schema.HTable.Vectorize ( happend )

23import Rel8.Table ( Table, Context, Columns, fromColumns, toColumns )

24import Rel8.Table.Alternative ( AltTable, (<|>:) )

25import Rel8.Table.Recontextualize ( Recontextualize )

28type NonEmptyTable :: Type -> Type

29newtype NonEmptyTable a =

30 NonEmptyTable (HNonEmptyTable (Columns a) (H (Context a)))

33instance Table context a => Table context (NonEmptyTable a) where

34 type Columns (NonEmptyTable a) = HNonEmptyTable (Columns a)

35 type Context (NonEmptyTable a) = Context a

37 fromColumns = NonEmptyTable

38 toColumns (NonEmptyTable a) = a

41instance Recontextualize from to a b =>

42 Recontextualize from to (NonEmptyTable a) (NonEmptyTable b)

45instance AltTable NonEmptyTable where

46 (<|>:) = (<>)

49instance Table DB a => Semigroup (NonEmptyTable a) where

50 NonEmptyTable as <> NonEmptyTable bs = NonEmptyTable $

51 happend (\_ _ (DB a) (DB b) -> DB (sappend1 a b)) as bs