src/Rel8/Query/Rebind.hs · rel8

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rel8/src/Rel8/Query/Rebind.hs

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1{-# language FlexibleContexts #-}

3module Rel8.Query.Rebind

4 ( rebind

5 )

6where

8-- base

9import Prelude

10import Control.Arrow ((<<<))

12-- opaleye

13import qualified Opaleye.Internal.Rebind as Opaleye

15-- rel8

16import Rel8.Expr ( Expr )

17import Rel8.Query ( Query )

18import Rel8.Table ( Table )

19import Rel8.Table.Opaleye ( unpackspec )

20import Rel8.Query.Opaleye (fromOpaleye)

23-- | 'rebind' takes a variable name, some expressions, and binds each of them

24-- to a new variable in the SQL. The @a@ returned consists only of these

25-- variables. It's essentially a @let@ binding for Postgres expressions.

26rebind :: Table Expr a => String -> a -> Query a

27rebind prefix a = fromOpaleye (Opaleye.rebindExplicitPrefix prefix unpackspec <<< pure a)