From d03d68c25f5f917b1736b5702a3abea288d54196 Mon Sep 17 00:00:00 2001
From: Joe Nelson <cred+github@begriffs.com>
Date: Sun, 22 Nov 2015 15:00:28 -0800
Subject: [PATCH] Simplify checking object keys for equality

---
 src/PostgREST/RequestIntent.hs | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/src/PostgREST/RequestIntent.hs b/src/PostgREST/RequestIntent.hs
index f802eac26..b21f45870 100644
--- a/src/PostgREST/RequestIntent.hs
+++ b/src/PostgREST/RequestIntent.hs
@@ -201,19 +201,14 @@ ensureUniform :: JSON.Array -> Maybe UniformObjects
 ensureUniform arr =
   let objs :: V.Vector JSON.Object
       objs = foldr -- filter non-objects, map to raw objects
-               (\result val -> case val of
+               (\val result -> case val of
                   JSON.Object o -> V.cons o result
                   _ -> result)
                V.empty arr
-      keysPerObj :: [S.Set T.Text]
-      keysPerObj = V.toList $ V.map (S.fromList . M.keys) objs
-      allKeys    :: S.Set T.Text
-      allKeys    = S.unions keysPerObj
-      commonKeys :: S.Set T.Text
-      commonKeys = case keysPerObj of
-                     h : _ -> foldr S.intersection h keysPerObj
-                     [] -> S.empty in
+      keysPerObj = V.map (S.fromList . M.keys) objs
+      canonicalKeys = fromMaybe S.empty $ keysPerObj V.!? 0
+      areKeysUniform = all (==canonicalKeys) keysPerObj in
 
-  if (length objs == length arr) && (allKeys == commonKeys)
+  if (V.length objs == V.length arr) && areKeysUniform
     then Just (UniformObjects objs)
     else Nothing