git.iko.soy/rel8
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rel8/src/Rel8/Column/Either.hs
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1{-# language DataKinds #-}
2{-# language StandaloneKindSignatures #-}
3{-# language TypeFamilyDependencies #-}
5module Rel8.Column.Either
6 ( HEither
7 )
8where
10-- base
11import Data.Kind ( Type )
12import Prelude
14-- rel8
15import qualified Rel8.Schema.Kind as K
16import Rel8.Schema.Result ( Result )
17import Rel8.Table.Either ( EitherTable )
20-- | Nest an 'Either' value within a 'Rel8able'. @HEither f a b@ will produce a
21-- 'EitherTable' @a b@ in the 'Expr' context, and a 'Either' @a b@ in the
22-- 'Result' context.
23type HEither :: K.Context -> Type -> Type -> Type
24type family HEither context = either | either -> context where
25 HEither Result = Either
26 HEither context = EitherTable context