updateWhere with SelectOpt

Currently selectList, updateWhere types is following:

selectList  :: [Filter val] -> [SelectOpt val] -> ReaderT backend m [Entity val]
updateWhere :: [Filter val] -> [Update val]    -> ReaderT backend m ()

But, I want to this.

updateWhere :: [Filter val] -> [Update val] -> [SelectOpt val] -> ReaderT backend m ()

Because, ran into this problem.

#!/usr/bin/env stack
-- stack --resolver lts-9.1 --install-ghc runghc --package persistent --package persistent-sqlite
{-# LANGUAGE EmptyDataDecls #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE GADTs #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE QuasiQuotes #-}
{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TypeFamilies #-}

import Control.Monad.IO.Class (liftIO)
import Database.Persist
import Database.Persist.Sqlite
import Database.Persist.TH

share
  [mkPersist sqlSettings, mkMigrate "migrateAll"]
  [persistLowerCase|
    Item
        name String
        order Int
        deriving Show
        UniqueOrder order
  |]

main :: IO ()
main =
  runSqlite ":memory:" $ do
    runMigration migrateAll
    t1 <- insert $ Item "test1" 1
    t2 <- insert $ Item "test2" 2
    t3 <- insert $ Item "test3" 3
    updateWhere [] [ItemOrder +=. 1] -- NG uniqueness error
    updateWhere [] [ItemOrder -=. 1] -- OK
    items <- selectList [] []
    liftIO $ print (items :: [Entity Item])
    deleteWhere ([] :: [Filter Item])

Error message;

test.hs: SQLite3 returned ErrorConstraint while attempting to perform step.

If can write updateWhere [] [ItemOrder +=. 1] [Desc ItemOrder] then nothing problem.

mysql 5.6 suport this syntax.

• 13.2.11 UPDATE Syntax

UPDATE [LOW_PRIORITY] [IGNORE] table_reference
    SET assignment_list
    [WHERE where_condition]
    [ORDER BY ...]
    [LIMIT row_count]

I tried make function updateWhereWithOpt, but many used internal functions.

• Referenced to Persist.Sql.Orphan.PersistQuery.hs

Can I submit PR?

Start in persistent/Database/Persist/Sql/Orphan/PersistQuery.hs around the referenced update functions and compare how selectList handles SelectOpt values. Use the supplied SQLite reproduction to define done: updateWhere accepts ordering options and the ordered increment avoids the uniqueness error, with the supported backend behavior covered.