From f54742186b0738804d85fafe0659f431f6f6f13b Mon Sep 17 00:00:00 2001
From: Joe Nelson <cred+github@begriffs.com>
Date: Fri, 20 Nov 2015 10:29:08 -0800
Subject: [PATCH] Use show instances for a shortcut

---
 src/PostgREST/App.hs           |  5 +----
 src/PostgREST/QueryBuilder.hs  | 16 ++--------------
 src/PostgREST/RequestIntent.hs |  6 +++++-
 src/PostgREST/Types.hs         | 11 +++++++++--
 4 files changed, 17 insertions(+), 21 deletions(-)

diff --git a/src/PostgREST/App.hs b/src/PostgREST/App.hs
index e08885acb..3009a4d8b 100644
--- a/src/PostgREST/App.hs
+++ b/src/PostgREST/App.hs
@@ -75,10 +75,7 @@ app dbStructure conf reqBody req =
   let
       -- TODO: blow up for Left values (there is a middleware that checks the headers)
       contentType = either (const ApplicationJSON) id (iAccepts intent)
-      contentTypeS ct = case ct of
-        ApplicationJSON -> "application/json"
-        TextCSV -> "text/csv"
-      contentTypeH = (hContentType, contentTypeS contentType) in
+      contentTypeH = (hContentType, cs $ show contentType) in
 
   case (iAction intent, iTarget intent, iPayload intent) of
 
diff --git a/src/PostgREST/QueryBuilder.hs b/src/PostgREST/QueryBuilder.hs
index f2a56d135..72ba5b8b1 100644
--- a/src/PostgREST/QueryBuilder.hs
+++ b/src/PostgREST/QueryBuilder.hs
@@ -321,20 +321,8 @@ orderF ts =
     queryTerm :: OrderTerm -> Text
     queryTerm t = " "
            <> cs (pgFmtIdent $ otTerm t) <> " "
-           <> sqlOrderDirection (otDirection t) <> " "
-           <> maybe "" sqlOrderNulls (otNullOrder t) <> " "
-
-sqlOrderDirection :: OrderDirection -> SqlFragment
-sqlOrderDirection d =
-  case d of
-    OrderDesc -> "desc"
-    OrderAsc  -> "asc"
-
-sqlOrderNulls :: OrderNulls -> SqlFragment
-sqlOrderNulls d =
-  case d of
-    OrderNullsFirst -> "nulls first"
-    OrderNullsLast  -> "nulls last"
+           <> (cs.show) (otDirection t) <> " "
+           <> maybe "" (cs.show) (otNullOrder t) <> " "
 
 insertableValue :: JSON.Value -> SqlFragment
 insertableValue JSON.Null = "null"
diff --git a/src/PostgREST/RequestIntent.hs b/src/PostgREST/RequestIntent.hs
index f1b369702..d00404b8e 100644
--- a/src/PostgREST/RequestIntent.hs
+++ b/src/PostgREST/RequestIntent.hs
@@ -32,6 +32,10 @@ data Target = TargetIdent QualifiedIdentifier
 -- | Enumeration of currently supported content types for
 -- route responses and upload payloads
 data ContentType = ApplicationJSON | TextCSV deriving Eq
+instance Show ContentType where
+  show ApplicationJSON = "application/json"
+  show TextCSV         = "text/csv"
+
 -- | When Hasql supports the COPY command then we can
 -- have a special payload just for CSV, but until
 -- then CSV is converted to a JSON array.
@@ -128,7 +132,7 @@ userIntent schema req reqBody =
   method          = requestMethod req
   isTargetingProc = fromMaybe False $ (== "rpc") <$> listToMaybe path
   hdrs            = requestHeaders req
-  qParams        = [(cs k, cs <$> v)|(k,v) <- queryString req]
+  qParams         = [(cs k, cs <$> v)|(k,v) <- queryString req]
   lookupHeader    = flip lookup hdrs
   hasPrefer val   = any (\(h,v) -> h == "Prefer" && v == val) hdrs
   singular        = hasPrefer "plurality=singular"
diff --git a/src/PostgREST/Types.hs b/src/PostgREST/Types.hs
index 02243c20a..0bea9245a 100644
--- a/src/PostgREST/Types.hs
+++ b/src/PostgREST/Types.hs
@@ -50,8 +50,15 @@ data PrimaryKey = PrimaryKey {
   , pkName  :: Text
 } deriving (Show, Eq)
 
-data OrderDirection = OrderAsc | OrderDesc deriving (Show, Eq)
-data OrderNulls = OrderNullsFirst | OrderNullsLast deriving (Show, Eq)
+data OrderDirection = OrderAsc | OrderDesc deriving (Eq)
+instance Show OrderDirection where
+  show OrderAsc  = "asc"
+  show OrderDesc = "desc"
+
+data OrderNulls = OrderNullsFirst | OrderNullsLast deriving (Eq)
+instance Show OrderNulls where
+  show OrderNullsFirst = "nulls first"
+  show OrderNullsLast  = "nulls last"
 
 data OrderTerm = OrderTerm {
   otTerm      :: Text