From 4b2670bf4394a5a3c559d2c46a3a66df4f7e8319 Mon Sep 17 00:00:00 2001
From: ncaq <ncaq@ncaq.net>
Date: Tue, 31 Jul 2018 17:20:29 +0900
Subject: [PATCH] added: instance Monad to Value

I see #94.
I think to can easy create monad instance.
---
 src/Database/Esqueleto/Internal/Language.hs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/Database/Esqueleto/Internal/Language.hs b/src/Database/Esqueleto/Internal/Language.hs
index f343838..b8d98d5 100644
--- a/src/Database/Esqueleto/Internal/Language.hs
+++ b/src/Database/Esqueleto/Internal/Language.hs
@@ -634,6 +634,10 @@ instance Applicative Value where
   (<*>) (Value f) (Value a) = Value (f a)
   pure = Value
 
+instance Monad Value where
+  (>>=) x f = valueJoin $ fmap f x
+    where valueJoin (Value v) = v
+
 -- | A list of single values.  There's a limited set of functions
 -- able to work with this data type (such as 'subList_select',
 -- 'valList', 'in_' and 'exists').