Quasi-quote the SQL

Fixes #1

PgStructure.hs

@@ -1,4 +1,4 @@
-{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE OverloadedStrings, QuasiQuotes #-}
 
 module PgStructure where
 
@@ -14,7 +14,7 @@ import qualified Data.Aeson as JSON
 import Database.PostgreSQL.Simple
 import Database.PostgreSQL.Simple.Types
 import Database.PostgreSQL.Simple.FromRow
---import Database.PostgreSQL.Simple.Arrays (esc)
+import Database.PostgreSQL.Simple.SqlQQ
 
 import Data.Aeson ((.=))
 
@@ -67,18 +67,20 @@ instance JSON.ToJSON Column where
 
 tables :: String -> Connection -> IO [Table]
 tables s conn = query conn q $ Only s
-  where q = "select table_schema, table_name,\
-            \       is_insertable_into \
-            \  from information_schema.tables\
-            \ where table_schema = ?"
+  where q = [sql|
+              select table_schema, table_name,\
+                     is_insertable_into \
+                from information_schema.tables\
+               where table_schema = ? |]
 
 columns :: T.Text -> Connection -> IO [Column]
 columns t conn = query conn q $ Only t
-  where q = "select table_schema, table_name, column_name, ordinal_position,\
-            \       is_nullable, data_type, is_updatable,\
-            \       character_maximum_length, numeric_precision\
-            \  from information_schema.columns\
-            \ where table_name = ?"
+  where q = [sql|
+              select table_schema, table_name, column_name, ordinal_position,
+                     is_nullable, data_type, is_updatable,
+                     character_maximum_length, numeric_precision
+                from information_schema.columns
+               where table_name = ? |]
 
 namedColumnHash :: [Column] -> HashMap String Column
 namedColumnHash = fromList . (Prelude.zip =<< Prelude.map colName)
@@ -90,6 +92,9 @@ printColumns :: T.Text -> Connection -> IO BL.ByteString
 printColumns table conn = JSON.encode . namedColumnHash <$> columns table conn
 
 selectAll :: T.Text -> Connection -> IO JSON.Value
-selectAll table conn = fromOnly <$> Prelude.head <$> query conn sql (Only $ QualifiedIdentifier (Just "base") table)
-  where sql = "select array_to_json(array_agg(row_to_json(t)))\
-            \  from (select * from ?) t;"
+selectAll table conn = fromOnly <$> Prelude.head <$> query conn q (Only safeName)
+  where
+    q = [sql|
+          select array_to_json(array_agg(row_to_json(t)))
+            from (select * from ?) t; |]
+    safeName = QualifiedIdentifier (Just "base") table